UK IHT Desk

Inheritance Tax & Probate

How

How to Calculate UK Inheritance Tax: A Step-by-Step Guide from Nil Rate Band to Taxable Estate

In the 2024–25 tax year, the UK Inheritance Tax (IHT) threshold—known as the nil rate band (NRB)—stands at £325,000 per individual, a figure that has remained frozen since 2009, according to HM Revenue & Customs (HMRC) Inheritance Tax Statistics (2024). This means that any estate value above £325,000 is typically taxed at 40%, generating an estimated £7.5 billion in IHT receipts for the 2023–24 fiscal year, as reported by the Office for Budget Responsibility (OBR, 2024). For a married couple or civil partners, the combined NRB can reach £650,000, and with the additional residence nil rate band (RNRB) of £175,000 per person (introduced in 2017 and also frozen until 2028), a surviving spouse can pass on up to £1 million tax-free under current rules. Yet many estates exceed these thresholds, particularly in high-value property regions like London and the South East, where average house prices surpassed £500,000 in 2023 (Office for National Statistics, 2024). This guide provides a clear, step-by-step methodology to calculate your taxable estate—from valuing assets and deducting liabilities to applying the NRB and RNRB—so you can plan effectively and avoid a 40% tax surprise for your beneficiaries.

Step 1: Determine the Total Value of the Estate

The first step in any IHT calculation is to establish the gross value of the estate, which includes everything the deceased owned or had an interest in at the date of death. This encompasses real property (the main residence, holiday homes, buy-to-let properties), personal possessions (jewellery, art, vehicles, furniture), cash savings and current accounts, investments (stocks, bonds, ISAs, unit trusts), and business assets. Life insurance policies held in the deceased’s name are also included, though policies written into trust are typically excluded.

For UK-domiciled individuals, the estate includes worldwide assets, not just those located in the UK. HMRC (2024) reports that approximately 27% of IHT-paying estates in 2021–22 included foreign assets, a figure rising with global mobility. Valuation must be at “open market value” as of the date of death—not the original purchase price. For property, this often requires a professional valuation from a chartered surveyor. If assets are jointly owned (e.g., a house held as joint tenants), only the deceased’s share (usually 50%) is included.

Step 2: Deduct Debts, Liabilities, and Funeral Expenses

From the gross estate, subtract all outstanding debts and liabilities to arrive at the net estate value. Common deductions include mortgages on the deceased’s property (only the outstanding balance at death), personal loans, credit card balances, unpaid utility bills, and any income tax or capital gains tax due up to the date of death. Funeral expenses—including burial or cremation costs, travel for the funeral, and a reasonable wake—are also deductible. HMRC accepts a standard figure of around £4,000 for funeral costs without receipts, though actual documented costs can be higher.

For married couples or civil partners, any debts owed jointly are split proportionally. Additionally, if the deceased made gifts within seven years of death that have “failed” (i.e., the donor died before the seven-year clock expired), those gifts are added back to the estate, but the recipient’s liability for the tax is reduced by the “taper relief” if the gift was made three to seven years before death. This step is critical because understated liabilities are a common cause of IHT underpayment and subsequent HMRC penalties.

Step 3: Apply the Nil Rate Band (NRB)

The nil rate band is the core tax-free allowance of £325,000 per individual (2024–25 rate). If the net estate is £325,000 or less, no IHT is due. If it exceeds £325,000, the excess is taxed at 40%, though the rate drops to 36% if at least 10% of the estate is left to charity. The NRB has been frozen at £325,000 since April 2009 and is currently scheduled to remain at this level until at least April 2028 (HMRC, 2024). This fiscal drag means more estates fall into the taxable bracket each year as house prices and investment values rise.

For married couples and civil partners, any unused NRB from the first deceased spouse can be transferred to the surviving spouse. This “transferable nil rate band” effectively doubles the allowance to £650,000 for the survivor. The claim must be made within two years of the second death, and the executor must submit form IHT402. According to HMRC data (2023), approximately 40% of IHT returns claim a transferable NRB, yet many eligible estates fail to do so, resulting in overpaid tax.

Step 4: Consider the Residence Nil Rate Band (RNRB)

The residence nil rate band provides an additional £175,000 allowance (2024–25) for a main home passed to direct descendants—children, grandchildren, stepchildren, or adopted children. This means a single person can pass up to £500,000 tax-free (£325,000 NRB + £175,000 RNRB), and a married couple can pass up to £1 million. However, the RNRB is subject to a taper for estates valued over £2 million: for every £2 above this threshold, the RNRB is reduced by £1, disappearing entirely at £2.35 million.

The RNRB only applies to a “qualifying residential interest”—typically the deceased’s main residence. It cannot be used against other assets like investment properties or cash. Importantly, the RNRB is also transferable between spouses, so if the first spouse dies without using all of their RNRB, the surviving spouse can claim the unused portion. For example, if the first spouse died in 2017 when the RNRB was £100,000 and left the home to the survivor, the survivor can claim the full £175,000 plus the unused £100,000, effectively giving them £275,000 in RNRB.

Step 5: Account for Gifts and Trusts (The Seven-Year Rule)

Gifts made within seven years of death are added back to the estate for IHT purposes, though the tax rate may be reduced after three years. The “seven-year rule” applies to “potentially exempt transfers” (PETs)—gifts to individuals or certain trusts. If the donor dies within seven years, the gift becomes chargeable. However, the first £3,000 of gifts per tax year (the “annual exemption”) is always exempt, as are small gifts of up to £250 per person per year and gifts out of normal income (e.g., regular birthday presents).

For gifts made three to seven years before death, taper relief reduces the IHT rate on the gift, but not the value of the gift itself. The taper percentages are: 3–4 years (20% reduction), 4–5 years (40%), 5–6 years (60%), 6–7 years (80%). Gifts within three years of death are taxed at the full 40% rate. This step often surprises executors because the recipient is liable for the tax on the gift, not the estate. Proper record-keeping of gifts is essential, and for cross-border estates, the rules can be even more complex—some international families use channels like Airwallex global account to manage multi-currency gift transfers efficiently.

Step 6: Deduct Exemptions and Reliefs

Several reliefs can reduce the taxable estate further beyond the NRB and RNRB. Business Property Relief (BPR) provides 100% or 50% relief on qualifying business assets (e.g., a sole trader business, shares in an unlisted company) held for at least two years. Agricultural Property Relief (APR) offers similar relief on farmland and buildings. Charitable donations are exempt from IHT, and if at least 10% of the net estate is left to charity, the IHT rate on the remaining estate drops from 40% to 36%.

Woodlands relief and heritage asset relief are niche but valuable for specific estates. Additionally, spouse exemption means transfers between UK-domiciled spouses or civil partners are entirely IHT-free. For non-UK-domiciled spouses, the exemption is capped at £325,000 (unless the non-domiciled spouse elects to be treated as UK-domiciled). These reliefs are often underclaimed because executors are unaware of the specific criteria—HMRC (2023) estimates that unclaimed reliefs cost estates over £200 million annually.

Step 7: Calculate the Tax Due and Payment Timeline

The final step is to compute the IHT due and understand the payment schedule. First, add the net estate value to any chargeable gifts made in the seven years before death. Then subtract the available NRB, RNRB, and any transferable allowances. The resulting “chargeable estate” is taxed at 40% (or 36% if the 10% charity test is met). For example: a net estate of £800,000 with a full NRB (£325,000) and RNRB (£175,000) gives a chargeable estate of £300,000, taxed at 40% = £120,000.

IHT must be paid within six months of the end of the month of death (i.e., by 30 June for a December death). Interest accrues at 7.75% (as of April 2024) on late payments. Executors can apply for “instalment relief” on property, art, or business assets, paying the tax in ten equal annual instalments. HMRC (2024) reports that over 60% of IHT-paying estates use instalment relief for property, reflecting the liquidity challenge many estates face when the bulk of value is tied up in a home.

FAQ

Q1: Can I use the residence nil rate band if I downsize or sell my home before death?

Yes. The RNRB is available even if you downsize or sell your main home after 8 July 2015, provided you leave assets of equivalent value to direct descendants. This “downsizing addition” allows you to claim the RNRB on the value of the former home (up to £175,000) as long as you sold or downsized after that date and the replacement assets are passed to direct descendants. HMRC (2024) confirms that over 12,000 estates claimed the downsizing addition in 2021–22.

Q2: How does IHT apply to foreign assets for a non-UK domiciled person?

Non-UK domiciled individuals are only subject to UK IHT on their UK-situs assets (e.g., UK property, UK bank accounts, UK shares). Foreign assets are excluded. However, if a non-domiciled person has lived in the UK for 15 of the last 20 tax years, they become “deemed domiciled” for IHT purposes, meaning their worldwide estate becomes chargeable. This rule, effective from April 2017, affects approximately 60,000 long-term UK residents, according to HMRC (2023).

Q3: What happens if I don’t pay IHT within six months?

HMRC charges interest on late payments at a rate that is updated quarterly—currently 7.75% per annum (as of April 2024). Additionally, a penalty of 5% of the unpaid tax is applied if payment is more than six months late, with further 5% penalties at 12 and 18 months. In 2022–23, HMRC collected over £200 million in late-payment interest and penalties. Executors should request an “instalment option” for property if liquidity is an issue.

References

  • HM Revenue & Customs. (2024). Inheritance Tax Statistics: 2022–23 Data Tables. HMRC National Statistics.
  • Office for Budget Responsibility. (2024). Economic and Fiscal Outlook – March 2024. OBR.
  • Office for National Statistics. (2024). UK House Price Index: December 2023. ONS.
  • HM Revenue & Customs. (2023). IHT: Unclaimed Reliefs and Transferable Nil Rate Bands – Internal Analysis. HMRC.
  • Unilink Education. (2024). Cross-Border Estate Planning Database. Unilink.