Category: Essentials of Economics: Ch 09

The past decade or so has seen large-scale economic turbulence. As we saw in the blog Fiscal impulses, governments have responded with large fiscal interventions. The COVID-19 pandemic, for example, led to a positive fiscal impulse in the UK in 2020, as measured by the change in the structural primary balance, of over 12 per cent of national income.

The scale of these interventions has led to a significant increase in the public-sector debt-to-GDP ratio in many countries. The recent interest rates hikes arising from central banks responding to inflationary pressures have put additional pressure on the financial well-being of governments, not least on the financing of their debt. Here we discuss these pressures in the context of the ‘r g’ rule of sustainable public debt.

Public-sector debt and borrowing

Chart 1 shows the path of UK public-sector net debt and net borrowing, as percentages of GDP, since 1990. Debt is a stock concept and is the result of accumulated flows of past borrowing. Net debt is simply gross debt less liquid financial assets, which mainly consist of foreign exchange reserves and cash deposits. Net borrowing is the headline measure of the sector’s deficit and is based on when expenditures and receipts (largely taxation) are recorded rather than when cash is actually paid or received. (Click here for a PowerPoint of Chart 1)

Chart 1 shows the impact of the fiscal interventions associated with the global financial crisis and the COVID-19 pandemic, when net borrowing rose to 10 per cent and 15 per cent of GDP respectively. The former contributed to the debt-to-GDP ratio rising from 35.6 per cent in 2007/8 to 81.6 per cent in 2014/15, while the pandemic and subsequent cost-of-living interventions contributed to the ratio rising from 85.2 per cent in 2019/20 to around 98 per cent in 2023/24.

Sustainability of the public finances

The ratcheting up of debt levels affects debt servicing costs and hence the budgetary position of government. Yet the recent increases in interest rates also raise the costs faced by governments in financing future deficits or refinancing existing debts that are due to mature. In addition, a continuation of the low economic growth that has beset the UK economy since the global financial crisis also has implications for the burden imposed on the public sector by its debts, and hence the sustainability of the public finances. After all, low growth has implications for spending commitments, and, of course, the flow of receipts.

The analysis therefore implies that the sustainability of public-sector debt is dependent on at least three factors: existing debt levels, the implied average interest rate facing the public sector on its debts, and the rate of economic growth. These three factors turn out to underpin a well-known rule relating to the fiscal arithmetic of public-sector debt. The rule is sometimes known as the ‘r g’ rule (i.e. the interest rate minus the growth rate).

Underpinning the fiscal arithmetic that determines the path of public-sector debt is the concept of the ‘primary balance’. This is the difference between the sector’s receipts and its expenditures less its debt interest payments. A primary surplus (a positive primary balance) means that receipts exceed expenditures less debt interest payments, whereas a primary deficit (a negative primary balance) means that receipts fall short. The fiscal arithmetic necessary to prevent the debt-to-GDP ratio rising produces the following stable debt equation or ‘r g’ rule:

On the left-hand side of the stable debt equation is the required primary surplus (PS) to GDP (Y) ratio. Moving to the right-hand side, the first term is the existing debt-to-GDP ratio (D/Y). The second term ‘r g’, is the differential between the average implied interest rate the government pays on its debt and the growth rate of the economy. These terms can be expressed in either nominal or real terms as this does not affect the differential.

To illustrate the rule consider a country whose existing debt-to-GDP ratio is 1 (i.e. 100 per cent) and the ‘r g’ differential is 0.02 (2 percentage points). In this scenario they would need to run a primary surplus to GDP ratio of 0.02 (i.e. 2 percent of GDP).

The ‘r g‘ differential

The ‘r g’ differential reflects macroeconomic and financial conditions. The fiscal arithmetic shows that these are important for the dynamics of public-sector debt. The fiscal arithmetic is straightforward when r = g as any primary deficit will cause the debt-to-GDP ratio to rise, while a primary surplus will cause the ratio to fall. The larger is g relative to r the more favourable are the conditions for the path of debt. Importantly, if the differential is negative (r < g), it is possible for the public sector to run a primary deficit, up to the amount that the stable debt equation permits.

Consider Charts 2 and 3 to understand how the ‘r g’ differential has affected debt sustainability in the UK since 1990. Chart 2 plots the implied yield on 10-year government bonds, alongside the annual rate of nominal growth (click here for a PowerPoint). As John explains in his blog The bond roller coaster, the yield is calculated as the coupon rate that would have to be paid for the market price of a bond to equal its face value. Over the period, the average annual nominal growth rate was 4.5 per cent, while the implied interest rate was almost identical at 4.6 per cent. The average annual rate of CPI inflation over this period was 2.8 per cent.

Chart 3 plots the ‘r g’ differential which is simply the difference between the two series in Chart 2, along with a 12-month rolling average of the differential to help show better the direction of the differential by smoothing out some of the short-term volatility (click here for a PowerPoint). The differential across the period is a mere 0.1 percentage points implying that macroeconomic and financial conditions have typically been neutral in supporting debt sustainability. However, this does mask some significant changes across the period.

We observe a general downward trend in the ‘r g’ differential from 1990 up to the time of the global financial crisis. Indeed between 2003 and 2007 we observe a favourable negative differential which helps to support the sustainability of public debt and therefore the well-being of the public finances. This downward trend of the ‘r g’ differential was interrupted by the financial crisis, driven by a significant contraction in economic activity. This led to a positive spike in the differential of over 7 percentage points.

Yet the negative differential resumed in 2010 and continued up to the pandemic. Again, this is indicative of the macroeconomic and financial environments being supportive of the public finances. It was, however, largely driven by low interest rates rather than by economic growth.

Consequently, the negative ‘r g’ differential meant that the public sector could continue to run primary deficits during the 2010s, despite the now much higher debt-to-GDP ratio. Yet, weak growth was placing limits on this. Chart 4 indeed shows that primary deficits fell across the decade (click here for a PowerPoint).

The pandemic and beyond

The pandemic saw the ‘r g’ differential again turn markedly positive, averaging 7 percentage points in the four quarters from Q2 of 2020. While the differential again turned negative, the debt-to-GDP ratio had also increased substantially because of large-scale fiscal interventions. This made the negative differential even more important for the sustainability of the public finances. The question is how long the negative differential can last.

Looking forward, the fiscal arithmetic is indeed uncertain and worryingly is likely to be less favourable. Interest rates have risen and, although inflationary pressures may be easing somewhat, interest rates are likely to remain much higher than during the past decade. Geopolitical tensions and global fragmentation pose future inflationary concerns and a further drag on growth.

As well as the short-term concerns over growth, there remain long-standing issues of low productivity which must be tackled if the growth of the UK economy’s potential output is to be raised. These concerns all point to the important ‘r g’ differential become increasingly less negative, if not positive. If so the fiscal arithmetic could mean increasingly hard maths for policymakers.




  1. What is meant by each of the following terms: (a) net borrowing; (b) primary deficit; (c) net debt?
  2. Explain how the following affect the path of the public-sector debt-to-GDP ratio: (a) interest rates; (b) economic growth; (c) the existing debt-to-GDP ratio.
  3. Which factors during the 2010s were affecting the fiscal arithmetic of public debt positively, and which negatively?
  4. Discuss the prospects for the fiscal arithmetic of public debt in the coming years.
  5. Assume that a country has an existing public-sector debt-to-GDP ratio of 60 percent.
    (a) Using the ‘rule of thumb’ for public debt dynamics, calculate the approximate primary balance it would need to run in the coming year if the expected average real interest rate on the debt were 3 per cent and real economic growth were 2 per cent?
    (b) Repeat (a) but now assume that real economic growth is expected to be 4 per cent.
    (c) Repeat (a) but now assume that the existing public-sector debt-to-GDP ratio is 120 per cent.
    (d) Using your results from (a) to (c) discuss the factors that affect the fiscal arithmetic of the growth of public-sector debt.

In his blog, The bond roller coaster, John looks at the pricing of government bonds and details how, in recent times, governments wishing to borrow by issuing new bonds are having to offer higher coupon rates to attract investors. The interest rate hikes by central banks in response to global-wide inflationary pressures have therefore spilt over into bond markets. Though this evidences the ‘pass through’ of central bank interest rate increases to the general structure of interest rates, it does, however, pose significant costs for governments as they seek to finance future budgetary deficits or refinance existing debts coming up to maturity.

The Autumn Statement in the UK is scheduled to be made on 22 November. This, as well as providing an update on the economy and the public finances, is likely to include a number of fiscal proposals. It is thus timely to remind ourselves of the size of recent discretionary fiscal measures and their potential impact on the sustainability of the public finances. In this first of two blogs, we consider the former: the magnitude of recent discretionary fiscal policy changes.

First, it is important to define what we mean by discretionary fiscal policy. It refers to deliberate changes in government spending or taxation. This needs to be distinguished from the concept of automatic stabilisers, which relate to those parts of government budgets that automatically result in an increase (decrease) of spending or a decrease (increase) in tax payments when the economy slows (quickens).

The suitability of discretionary fiscal policy measures depends on the objectives they trying to fulfil. Discretionary measures can be implemented, for example, to affect levels of public-service provision, the distribution of income, levels of aggregate demand or to affect longer-term growth of aggregate supply. As we shall see in this blog, some of the large recent interventions have been conducted primarily to support and stabilise economic activity in the face of heightened economic volatility.

Discretionary fiscal measures in the UK are usually announced in annual Budget statements in the House of Commons. These are normally in March, but discretionary fiscal changes can be made in the Autumn Statement too. The Autumn Statement of October 2022, for example, took on significant importance as the new Chancellor of the Exchequer, Jeremy Hunt, tried to present a ‘safe pair hands’ following the fallout and market turbulence in response to the fiscal statement by the former Chancellor, Kwasi Kwarteng, on 23 September that year.

The fiscal impulse

The large-scale economic turbulence of recent years associated first with the global financial crisis of 2007–9 and then with the COVID-19 pandemic and the cost-of-living crisis, has seen governments respond with significant discretionary fiscal measures. During the COVID-19 pandemic, examples of fiscal interventions in the UK included the COVID-19 Business Interruption Loan Scheme (CBILS), grants for retail, hospitality and leisure businesses, the COVID-19 Job Retention Scheme (better known as the furlough scheme) and the Self-Employed Income Support Scheme.

The size of discretionary fiscal interventions can be measured by the fiscal impulse. This captures the magnitude of change in discretionary fiscal policy and thus the size of the stimulus. The concept is not to be confused with fiscal multipliers, which measure the impact of fiscal changes on economic outcomes, such as real national income and employment.

By measuring fiscal impulses, we can analyse the extent to which a country’s fiscal stance has tightened, loosened, or remained unchanged. In other words, we are attempting to capture discretionary fiscal policy changes that result in structural changes in the government budget and, therefore, in structural changes in spending and/or taxation.

To measure structural changes in the public-sector’s budgetary position, we calculate changes in structural budget balances.

A budget balance is simply the difference between receipts (largely taxation) and spending. A budget surplus occurs when receipts are greater than spending, while a deficit (sometimes referred to as net borrowing) occurs if spending is greater than receipts.

A structural budget balance cyclically-adjusts receipts and spending and hence adjusts for the position of the economy in the business cycle. In doing so, it has the effect of adjusting both receipts and spending for the effect of automatic stabilisers. Another way of thinking about this is to ask what the balance between receipts and spending would be if the economy were operating at its potential output. A deterioration in a structural budget balance infers a rise in the structural deficit or fall in the structural surplus. This indicates a loosening of the fiscal stance. An improvement in the structural budget balance, by contrast, indicates a tightening.

The size of UK fiscal impulses

A frequently-used measure of the fiscal impulse involves the change in the cyclically-adjusted public-sector primary deficit.

A primary deficit captures the extent to which the receipts of the public sector fall short of its spending, excluding its spending on debt interest payments. It essentially captures whether the public sector is able to afford its ‘new’ fiscal choices from its receipts; it excludes debt-servicing costs, which can be thought of as reflecting fiscal choices of the past. By using a cyclically-adjusted primary deficit we are able to isolate more accurately the size of discretionary policy changes. Chart 1 shows the UK’s actual and cyclically-adjusted primary deficit as a share of GDP since 1975, which have averaged 1.3 and 1.1 per cent of GDP respectively. (Click here for a PowerPoint of the chart.)

The size of the fiscal impulse is measured by the year-on-year percentage point change in the cyclically-adjusted public-sector primary deficit as a percentage of potential GDP. A larger deficit or a smaller surplus indicates a fiscal loosening (a positive fiscal impulse), while a smaller deficit or a larger surplus indicates a fiscal tightening (a negative fiscal impulse).

Chart 2 shows the magnitude of UK fiscal impulses since 1980. It captures very starkly the extent of the loosening of the fiscal stance in 2020 in response to the COVID-19 pandemic. (Click here for a PowerPoint of the chart.) In 2020 the cyclically-adjusted primary deficit to potential output ratio rose from 1.67 to 14.04 per cent. This represents a positive fiscal impulse of 12.4 per cent of GDP.

A tightening of fiscal policy followed the waning of the pandemic. 2021 saw a negative fiscal impulse of 10.1 per cent of GDP. Subsequent tightening was tempered by policy measures to limit the impact on the private sector of the cost-of-living crisis, including the Energy Price Guarantee and Energy Bills Support Scheme.

In comparison, the fiscal response to the global financial crisis led to a cumulative increase in the cyclically-adjusted primary deficit to potential GDP ratio from 2007 to 2009 of 5.0 percentage points. Hence, the financial crisis saw a positive fiscal impulse of 5 per cent of GDP. While smaller in comparison to the discretionary fiscal responses to the COVID-19 pandemic, it was, nonetheless, a sizeable loosening of the fiscal stance.

Sustainability and well-being of the public finances

The recent fiscal interventions have implications for the financial well-being of the public-sector. Not least, the financing of the positive fiscal impulses has led to a substantial growth in the accumulated size of the public-sector debt stock. At the end of 2006/7 the public-sector net debt stock was 35 per cent of GDP; at the end of the current financial year, 2023/24, it is expected to be 103 per cent.

As we saw at the outset, in an environment of rising interest rates, the increase in the public-sector debt to GDP ratio creates significant additional costs for government, a situation that is made more difficult for government not only by the current flatlining of economic activity, but by the low underlying rate of economic growth seen since the financial crisis. The combination of higher interest rates and lower economic growth has adverse implications for the sustainability of the public finances and the ability of the public sector to absorb the effects of future economic crises.



  • IFS Green Budget
  • Institute for Fiscal Studies, Carl Emmerson, Paul Johnson and Ben Zaranko (eds) (October 2023)



  1. Explain what is meant by the following fiscal terms: (a) structural deficit; (b) automatic stabilisers; (c) discretionary fiscal policy; (d) primary deficit.
  2. What is the difference between current and capital public expenditures? Give some examples of each.
  3. Consider the following two examples of public expenditure: grants from government paid to the private sector for the installation of energy-efficient boilers, and welfare payments to unemployed people. How are these expenditures classified in the public finances and what fiscal objectives do you think they meet?
  4. Which of the following statements about the primary balance is FALSE?
    (a) In the presence of debt interest payments a primary deficit will be smaller than a budget deficit.
    (b) In the presence of debt interest payments a primary surplus will be smaller than a budget surplus.
    (c) The primary balance differs from the budget balance by the size of debt interest payments.
    (d) None of the above.
  5. Explain the difference between a fiscal impulse and a fiscal multiplier.
  6. Why is low economic growth likely to affect the sustainability of the public finances? What other factors could also matter?

The distinction between nominal and real values in one of the ‘threshold concepts’ in economics. These are concepts that are fundamental to a discipline and which occur again and again. The distinction between nominal and real values is particularly important when interpreting and analysing data. We show its importance here when analysing the latest retail sales data from the Office for National Statistics.

Retail sales relate to spending on items such as food, clothing, footwear, and household goods (see). They involve sales by retailers directly to end consumers whether in store or online. The retail sales index for Great Britain is based on a monthly survey of around 5000 retailers across England, Scotland and Wales and is thought to capture around 93 per cent of turnover in the sector.

Estimates of retail sales are published in index form. There are two indices published by the ONS: a value and volume measure. The value index reflects the total turnover of business, while the volume index adjusts the value index for price changes. Hence, the value estimates are nominal, while the volume estimates are real. The key point here is that the nominal estimates reflect both price and volume changes, whereas the real estimates adjust for price movements to capture only volume changes.

The headline ONS figures for September 2023 showed a 0.9 per cent volume fall in the volume of retail sales, following a 0.4 per cent rise in August. In value terms, September saw a 0.2 per cent fall in retail sales following a 0.9 per cent rise in August. Monthly changes can be quite volatile, even after seasonal adjustment, and sensitive to peculiar factors. For example, the unusually warm weather this September helped to depress expenditure on clothes. It is, therefore, sensible to take a longer-term view when looking for clearer patterns in spending behaviour.

Chart 1 plots the value and volume of retail sales in Great Britain since 1996. (Click here for a PowerPoint of this and the other two charts). In value terms, retail sales spending increased by 165 per cent, whereas in volume terms, spending increased by 73 per cent. This difference is expected in the presence of rising prices, since nominal growth, as we have just noted, reflects both price and volume changes. The chart is notable for capturing two periods where the volume of retail spending ceased to grow. The first of these is following the global financial crisis of the late 2000s. The period from 2008 to 2013 saw the volume of retail sales stagnate and flatline with a recovery in volumes only really starting to take hold in 2014. Yet in nominal terms retail sales grew by around 16 per cent.

The second of the two periods is the decline in the volume of retail sales from 2021. To help illustrate this more clearly, Chart 2 zooms in on retail sales over the past five years or so. We can see a significant divergence between the volume and value of retail sales. Between April 2021 and September 2023, the volume of retail sales fell by 11%. In contrast, the value of retail sales increased by 8.4%. The impact of the inflationary shock and the consequent cost-of-living crisis that emerged from 2021 is therefore demonstrated starkly by the chart, not least the severe drag that it has had on the volume of retail spending. This has meant that the aggregate volume of retail sales in September 2023 was only back to the levels of mid-2018.

Finally, Chart 3 shows the patterns in the volumes of retailing by four categories since 2018: specifically, food stores, predominantly non-food stores, non-store retail, and automotive fuel. The largest fall in the volume of retail sales has been experienced by non-store retailing – largely online retailing. From its peak in December 2021, non-store retail sales decreased by 18% up to September 2023. While this needs to be set in the context of the volume of non-store retail purchases being 15% higher than in February 2020 before the pandemic lockdowns were introduced, it is nonetheless indicative of the pressures facing online retailers.

Importantly, the final chart shows that the pressures in retailing are widespread. Spending volumes on automotive fuels, and in food and non-food stores are all below 2019 levels. The likelihood is that these pressures will persist for some time to come. This inevitably has potential implications for retailers and, of course, for those that work in the sector.


Statistical bulletin



  1. Why does an increase in the value of retail sales not necessarily mean that their volume has increased?
  2. In the presence of deflation, which will be higher: nominal or real growth rates?
  3. Discuss the factors that could explain the patterns in the volume of spending observed in the different categories of retail sales in Chart 3.
  4. Discuss what types of retail products might be more or less sensitive to the macroeconomic environment.
  5. Conduct a survey of recent media reports to prepare a briefing discussing examples of retailers who have struggled or thrived in the recent economic environment.
  6. What do you understand by the concepts of ‘consumer confidence’ and ‘economic uncertainty’? How might these affect the volume of retail spending?
  7. Discuss the proposition that the retail sales data cast doubt on whether people are ‘forward-looking consumption smoothers’.

Central bankers, policymakers, academics and economists met at the Economic Symposium at Jackson Hole, Wyoming from August 24–26. This annual conference, hosted by Kansas City Fed, gives them a chance to discuss current economic issues and the best policy responses. The theme this year was ‘Structural Shifts in the Global Economy’ and one of the issues discussed was whether, in the light of such shifts, central banks’ 2 per cent inflation targets are still appropriate.

Inflation has been slowing in most countries, but is still above the 2 peer cent target. In the USA, CPI inflation came down from a peak of 9.1% in June 2022 to 3.2% in July 2023. Core inflation, however, which excludes food and energy was 4.7%. At the symposium, in his keynote address the Fed Chair, Jay Powell, warned that despite 11 rises in interest rates since April 2022 (from 0%–0.25% to 5%–5.25%) having helped to bring inflation down, inflation was still too high and that further rises in interest rates could not be ruled out.

We are prepared to raise rates further if appropriate, and intend to hold policy at a restrictive level until we are confident that inflation is moving sustainably down toward our objective.

However, he did recognise the need to move cautiously in terms of any further rises in interest rates as “Doing too much could also do unnecessary harm to the economy.” But, despite the rises in interest rates, growth has remained strong in the USA. The annual growth rate in real GDP was 2.4% in the second quarter of 2023. Unemployment, at 3.5%, is low by historical standards and similar to the rate before the Fed began raising interest rates.

Raising the target rate of inflation?

Some economists and politicians have advocated raising the target rate of inflation from 2 per cent to, perhaps, 3 per cent. Jason Furman, an economic policy professor at Harvard and formerly chief economic advisor to President Barack Obama, argues that a higher target has the benefit of helping cushion the economy against severe recessions, especially important when such there have been adverse supply shocks, such as the supply-chain issues following the COVID lockdowns and then the war in Ukraine. A higher inflation rate may encourage more borrowing for investment as the real capital sum will be eroded more quickly. Some countries do indeed have higher inflation targets, as the table shows.

Powell emphatically ruled out any adjustment to the target rate. His views were expanded upon by Christine Lagarde, the head of the European Central Bank. She argued that in a world of greater supply shocks (such as from climate change), greater frictions in markets and greater inelasticity in supply, and hence greater price fluctuations, it is important for wage increases not to chase price increases. Increasing the target rate of inflation would anchor inflationary expectations at a higher level and hence would be self-defeating. Inflation in the eurozone, as in the USA, is falling – it halved from a peak of 10.6% in 2022 to 5.3% in July this year. Given this and worries about recession, the ECB may not raise interest rates at its September meeting. However, Lagarde argued that interest rates needed to remain high enough to bring inflation back to target.

The UK position

The Bank of England, too, is committed to a 2 per cent inflation target, even though the inflationary problems for the UK economy are greater that for many other countries. Greater shortfalls in wage growth have been more concentrated amongst lower-paid workers and especially in the public health, safety and transport sectors. Making up these shortfalls will slow the rate of inflationary decline; resisting doing so could lead to protracted industrial action with adverse effects on aggregate supply.

Then there is Brexit, which has added costs and bureaucratic procedures to many businesses. As Adam Posen (former member of the MPC) points out in the article linked below:

Even if this government continues to move towards more pragmatic relations with the EU, divergences in standards and regulation will increase costs and decrease availability of various imports, as will the end of various temporary exemptions. The base run rate of inflation will remain higher for some time as a result.

Then there is a persistent problem of low investment and productivity growth in the UK. This restriction on the supply side will make it difficult to bring inflation down, especially if workers attempt to achieve pay increases that match cost-of-living increases.

Sticking to the status quo

There seems little appetite among central bankers to adjust inflation targets. Squeezing inflation out of their respective economies is painful when inflation originates largely on the supply side and hence the problem is how to reduce demand and real incomes below what they would otherwise have been.

Raising inflation targets, they argue, would not address this fundamental problem and would probably simply anchor inflationary expectations at the higher level, leaving real incomes unchanged. Only if such policies led to a rise in investment would a higher target be justified and central bankers do not believe that it would.




  1. Use an aggregate demand and supply diagram (AD/AS or DAD/DAS) to illustrate inflation since the opening up of economies after the COVID lockdowns. Use another one to illustrate the the effects of central banks raising interest rates?
  2. Why is the world likely to continue experiencing bigger supply shocks and greater price volatility than before the pandemic?
  3. With hindsight, was increasing narrow money after the financial crisis and then during the pandemic excessive? Would it have been better to have used the extra money to fund government spending on infrastructure rather than purchasing assets such as bonds in the secondary market?
  4. What are the arguments for and against increasing the target rate of inflation?
  5. How do inflationary expectations influence the actual rate of inflation?
  6. Consider the arguments for and against the government matching pay increases for public-sector workers to the cost of living.

In this third blog about inflation, we focus on monetary policy to deal with the problem and bring inflation back to the target rate, which is typically 2 per cent around the world (including the eurozone, the USA and the UK). We ask the questions: was the response of central banks too timid initially, meaning that harsher measures had to be taken later; and will these harsher measures turn out to be excessive? In other words, has the eventual response been ‘too much, too late’, given that the initial measures were too little?

Inflation rates began rising in the second half of 2021 as economies began to open up as the pandemic subsided. Supply-chain problems drove the initial rise in prices. Then, following the Russian invasion of Ukraine in February 2022 and the adverse effects on oil, gas and grain prices, inflation rose further. In the UK, CPI inflation peaked at 11.1% in October 2022 (see chart 1 in the first of these three blogs). Across the whole EU-27, it peaked at 11.5% in October 2022; US inflation peaked at 9.1% in June 2022; Japanese inflation peaked at 4.3% in January 2023.

This raises the questions of why interest rates were not raised by a greater amount earlier (was it too little, too late?) and why they have continued to be raised once inflation rates have peaked (is it too much, too late?).

The problem of time lags

Both inflation and monetary policy involve time lags. Rising costs take a time to work their way through the supply chain. Firms may use old stocks for a time which are at the original price. If it is anticipated that costs will rise, central banks will need to take action early and not wait until all cost increases have worked their way through to retail prices.

In terms of monetary policy, the lags tend to be long.

If central bank interest rates are raised, it may take some time for banks to raise savings rates – a common complaint by savers.

As far as borrowing rates are concerned, as we saw in the previous blog, loans secured on dwellings (mortgages) account for the majority of households’ financial liabilities (76.4% in 2021) and here the time lags between central bank interest rate changes and changes in people’s mortgage interest rates can be very long. Only around 14 of UK mortgages are at variable rates; the rest are fixed, typically for between 2 to 5 years. So, when Bank Rate changes, people on fixed rates will be unaffected until their mortgage comes up for renewal, when they can be faced with a huge increase in payments.

Only around 21% of mortgages in England were/are due for renewal in 2023, and with 57% of these the old fixed rates were below 2%. Currently (July 2023), the average two-year fixed-rate mortgage rate in the UK is 6.81% (based on 75% loan to value (LTV)); the average five-year rate is 6.31% (based on 75% LTV). This represents a massive increase in interest rates, but for a relatively small proportion of homeowners and an even smaller proportion of total households.

But as more and more fixed-rate mortgages come up for renewal, so the number of people affected will grow, as will the dampening effect on aggregate demand as such people are forced to cut back on spending. This dampening effect will build up for many months.

And there is another time lag – that between prices and wages. Wages are negotiated periodically, normally annually or sometimes less frequently. Employees will typically seek a cost-of-living element in wage rises that covers price rises over the past 12 months, not inflation in the past month. If inflation is rising (or falling), such negotiations will not reflect the current situation. There is thus a time lag built in to such negotiations. Even if higher interest rates reduce inflation, the full effect can take some time because of this wages time lag.

Other time lags include those involving ongoing capital projects. If construction is taking place, it will take some time to complete and in the meantime is unlikely to be stopped. Higher interest rates will affect capital investment decisions now, but existing projects are likely to continue to completion. As more projects are completed over time, so the effect of higher interest rates is likely to accumulate.

Then there is the question of savings. During the pandemic, many people increased their savings as their opportunities for spending were more limited. Since then, many people have drawn on these savings to fund holidays, eating out and other leisure activities. Such spending is likely to taper off as savings are reduced. Again, the interest rises may prove to have been excessive as a means of reducing aggregate demand.

These time lags suggest that after some months the economy will have been excessively dampened and that the policy will have ‘overshot’ the mark. Had interest rates been raised more rapidly earlier and by larger amounts, the peak level of rates may not have needed to be so high.

Perhaps one of the biggest worries about raising interest rates excessively because of time lags is the effect on corporate and government debt. Highly indebted companies and countries will find that a large increase in interest rates makes servicing their debt much harder. For example, Thames Water, the UK’s biggest water and sewerage company accumulated some £14 billion in debt during the era of low interest rates. It has now declared that it cannot service these debts and is on the brink of insolvency. In the case of governments, as increasing amounts have to be spent on servicing their debt, so they may be forced to cut expenditure elsewhere. This will have a dampening effect on the economy – but with a time lag.

The distribution of pain

Those with large credit-card debt and large mortgages coming up for renewal or at variable rates will have borne the brunt of interest rate rises. These people, such as young people with families, are often those most affected by inflation, with a larger proportion of their expenditure on energy and food. Other people adversely affected are tenants where landlords raise rents to cover their higher mortgage payments.

Those with no debts will have been little affected by the hike in interest rates, unless the curbing of aggregate demand affects their chances of overtime or reduces available shifts or, worse still, leads to redundancy.

Excessive rises in interest rates exacerbate these distributional effects.



  1. For what reasons might a central bank be unwilling to raise interest rates by more than 0.25 or 0.5 percentage points per month?
  2. What instruments other than changing interest rates does a central bank have for influencing aggregate demand?
  3. Distinguish between demand-pull and cost-push inflation.
  4. Why might using interest rates to curb inflation be problematic when inflation is caused by adverse supply shocks?
  5. How are expectations of consumers and firms relevant in determining (a) the appropriate monetary policy measures and (b) their effectiveness?
  6. How could a careful use of a combination of monetary and fiscal policies reduce the redistributive effects of monetary policy?
  7. How might the use of ‘forward guidance’ by central banks reduce the need for such large rises in interest rates?