This Forecast in-depth page has been updated with information available at the time of the March  2022 Economic and fiscal outlook.

Inheritance tax (IHT) is usually levied on the value of all the assets in an individual’s estate on death, after deducting any liabilities, exemptions and reliefs. Assets left to a spouse or civil partner of the deceased are usually exempt, as are assets left to a charity. In 2022-23 we forecast that IHT will raise £6.7 billion. This represents 0.7 per cent of all receipts and is equivalent to 0.3 per cent of national income.

The rate of IHT is normally 40 per cent on the value of an estate above a threshold of £325,000. This threshold is frozen up to and including 2025-26. Any unused threshold may be transferred to a surviving spouse or civil partner, increasing their combined threshold to up to £650,000. There is an additional transferrable main residence nil rate band of £175,000 available when a home is left to children or other direct descendants. The rate of IHT is reduced to 36 per cent if 10 per cent or more of the net value of the estate above the threshold is left to charity.

  Forecast methodology

Forecast process

The OBR commissions forecasts of IHT from HM Revenue and Customs (HMRC) for each fiscal event. The forecasts start by generating an in-year estimate for receipts in the current year, then use a model to forecast growth in receipts from that starting point. We provide HMRC with economic forecasts that are used to generate the tax forecasts. These are scrutinised in a challenge process that typically involves two rounds of meetings where HMRC analysts present forecasts to the Budget Responsibility Committee and OBR staff. This process allows the BRC to refine the assumptions and judgements that underpin the forecasts before they are published in our Economic and fiscal outlooks (EFOs).

Forecasting models

The IHT forecast is based on a micro-simulation model. Administrative data on a sample of estates are used to estimate the total population of estates being passed on at the point of liable deaths and the amount of tax due on those estates. The data are projected forward using our forecasts for things like house prices and equity prices. Except where the threshold has already been announced (it is currently frozen up to and including 2025-26), the Government’s default indexation assumption is that IHT thresholds rise in line with CPI inflation. The number of deaths is projected in line with the ONS principal population projection.

Main forecast determinants

The main determinants of our IHT forecast are those related to the tax base, i.e. the various types of financial and non-financial assets left upon death. See the ready reckoners section below for more information on the main effects of these determinants on IHT receipts.

Main forecast judgements

The main forecast judgement in the IHT forecast relates to the starting point from which the model is applied:

    • In-year estimate – our estimate for IHT receipts in the current year is determined by year-to-date performance of receipts and indications from HMRC’s internal receipts monitoring. The in-year estimate determines the starting point from which we use our model to forecast receipts growth. For IHT, this judgement is often affected by large one-off payments from high-value estates, where we need to determine the extent to which such payments should be assumed to repeat in future years.

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  Previous forecasts

Since June 2010, IHT receipts have been consistently stronger than our forecasts. This partly reflects stronger-than-expected average house price inflation from our March 2013 forecast onwards. But it also reflects under-estimates in our forecasts for the average value of estates subject to IHT, which partly reflects trends at the top-end of the property market.

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  Policy measures

Since our first forecast in June 2010, governments have announced several policy measures affecting our forecast for IHT receipts. The original costings for these measures are contained in our policy measures database and were described briefly in the Treasury’s relevant Policy costings document. For measures announced since December 2014, the uncertainty ranking that we assigned to each is set out in a separate database. For those deemed ‘high’ or ‘very high’ uncertainty, the rationale for that ranking was set out in Annex A of the relevant Economic and fiscal outlook. These policy costings include:

  • a reduction in the rate to 36 per cent for estates with charitable donations of more than 10 per cent from 2012-13, announced at Budget 2011;
  • freezes to the threshold to keep it at £325,000 were announced at the Budget 2010, Budget 2013 and the July 2015 Budget, and again at the March 2021 Budget. It is due to remain at this level until 2025-26; and
  • the introduction of a transferrable main residence nil rate band starting at £100,000 in 2017-18, rising in stages to £175,000 by 2020-21, was announced at the July 2015 Budget. This has raised a married couple’s tax-free threshold for their main residence to £1 million.

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  Ready reckoners

‘Ready reckoners’ show how our fiscal forecasts could be affected by changes in selected economic determinants. They are stylised quantifications that reflect the typical impact of changes in economic variables on receipts and spending. These estimates are specific to our October 2021 forecast and we would expect them to become outdated over time, as the economy and public finances, and the policy setting, continue to evolve. They are subject to uncertainty because they are based on models that draw on historical relationships or simulations of policy settings. More information can be found in the ‘ready reckoners’ spreadsheet available on our Data page.

The table below shows that:

    • Property prices and equity prices affect the value of assets subject to IHT, with property prices roughly twice as important (in line with their share of the value of assets liable to IHT).

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Other taxes