UK IHT Desk

Inheritance Tax & Probate

可转移免税额规则：从已故

可转移免税额规则：从已故配偶继承的额外免税额度怎么用

In the 2024-25 tax year, the standard Inheritance Tax (IHT) nil-rate band (NRB) remains frozen at £325,000 per individual, a level unchanged since 2009, according to HM Revenue & Customs (HMRC) Inheritance Tax Statistics (2024). However, a critical and often underused provision—the transferable nil-rate band (TNRB)—allows a surviving spouse or civil partner to claim any unused portion of their deceased partner’s NRB, effectively doubling the potential tax-free threshold on their own estate to as much as £650,000. HMRC data shows that over 90% of estates with a surviving spouse are eligible for this relief, yet many fail to formally claim it, leaving families exposed to an unnecessary 40% tax charge on assets that could have passed entirely tax-free. For a married couple with combined assets exceeding £325,000, understanding how to inherit and deploy the unused NRB from a first death is not merely a planning luxury—it is a structural necessity for preserving generational wealth. This article explains the mechanics of the TNRB, the interaction with the residence nil-rate band (RNRB), and the practical steps required to secure the full allowance.

The Core Mechanics of the Transferable Nil-Rate Band

The transferable nil-rate band (TNRB) operates on a straightforward principle: when the first spouse or civil partner dies, any portion of their £325,000 NRB that was not used against their estate can be transferred to the surviving partner. This is not an automatic process—the executor of the first estate must formally elect to transfer the unused percentage on the IHT account (form IHT402) within two years of the death, though HMRC generally accepts late claims up to four years.

The calculation is based on a percentage, not a fixed pound figure. For example, if the first deceased spouse used only £100,000 of their NRB (leaving 69.23% unused), the survivor’s estate will inherit exactly 69.23% of the prevailing NRB at the time of the second death. If the NRB is still £325,000 at the second death, that means an extra £225,000 of tax-free allowance. This percentage-based approach protects the transfer from future NRB freezes or increases, though the current political environment suggests the £325,000 figure may remain static until at least 2028.

Key nuance: The TNRB applies only to spouses and civil partners—unmarried cohabitees do not qualify, regardless of relationship duration or shared financial arrangements. This makes marriage or civil partnership registration a critical structural decision for IHT planning purposes.

Interaction with the Residence Nil-Rate Band

Since April 2017, the residence nil-rate band (RNRB) has added a further £175,000 per individual (2024-25 rate) where a main residence is passed to direct descendants. The TNRB and RNRB can be combined, creating a potential total tax-free threshold of up to £1 million for a married couple: £325,000 NRB + £325,000 transferred NRB + £175,000 RNRB + £175,000 transferred RNRB.

However, the RNRB has strict eligibility conditions. The property must have been the deceased’s home at some point, and it must pass to children, grandchildren, or step-descendants. Estates valued over £2 million face a tapered withdrawal of the RNRB at a rate of £1 lost for every £2 above the threshold. For a couple with a modest home but significant investment portfolios, the RNRB may be unavailable, making the TNRB the primary tool for sheltering wealth.

A common planning error is assuming the RNRB transfers automatically alongside the TNRB. While the mechanism is similar—a separate claim on form IHT402—the RNRB transfer is only available if the first death occurred on or after 6 April 2017. For earlier deaths, no RNRB transfer is possible, and the survivor can only claim the standard TNRB.

Practical Claim Process: Form IHT402 and Deadlines

Securing the TNRB requires a formal claim via HMRC form IHT402, which must be submitted alongside the IHT400 account for the first estate. The claim must include a calculation of the unused percentage, supported by a breakdown of the first deceased’s assets, liabilities, and any gifts made in the seven years before death.

The critical deadline is two years from the end of the month of the first death. HMRC publishes statistics showing that approximately 15% of claims are submitted late, often resulting in unnecessary correspondence and, in rare cases, loss of the relief. Executors should file the claim even if the first estate was below the NRB threshold and no IHT was due—the unused percentage is still 100%, and the transfer is valuable for the survivor’s future planning.

For estates where the first death occurred many years ago, the survivor can still make a late claim, but HMRC will require an explanation. Accepted reasons include the survivor being unaware of the relief or the original executor failing to file. The claim is made on the survivor’s own IHT account at their death, with supporting documentation from the first estate.

Case Study: Mr and Mrs A—Maximising the Combined Allowance

Mr A died in 2020, leaving his entire estate of £400,000 to his wife, Mrs A. Because of the spouse exemption, no IHT was due, and 100% of his £325,000 NRB remained unused. Mrs A’s executor filed form IHT402 within six months, securing a 100% transfer of the NRB.

Mrs A died in 2024, owning a house worth £500,000 (left to her daughter), plus £300,000 in savings and investments. Her total estate was £800,000. Her available NRB: her own £325,000 plus the transferred 100% of Mr A’s £325,000 = £650,000. She also qualified for the full RNRB of £175,000 because the house passed to her daughter, and the estate was under £2 million. Total allowances: £825,000. Taxable estate: £800,000 minus £825,000 = £0. No IHT was payable.

Had the TNRB not been claimed, Mrs A’s estate would have had only £500,000 in allowances (her NRB plus her RNRB), leaving £300,000 taxable at 40%—a £120,000 tax bill. The form IHT402 saved the family a six-figure sum.

Common Mistakes and How to Avoid Them

Three recurring errors undermine TNRB claims. First, failing to file the claim at all—some executors assume the transfer is automatic, which it is not. Second, miscalculating the unused percentage by including exempt gifts (such as charitable donations) in the used portion, when only chargeable transfers reduce the NRB. Third, ignoring the TNRB when the first estate was modest—even a £10,000 estate leaves 96.9% of the NRB unused.

Another trap involves lifetime gifts. If the first spouse made large gifts within seven years of death that exceeded their annual exemption, those gifts reduce the available NRB for transfer. Executors must reconstruct the gift history accurately.

For cross-border estates, the TNRB can still apply if the first spouse was domiciled in the UK, but the interaction with foreign inheritance tax systems is complex. Some international families use channels like Airwallex global account to manage cross-border asset transfers and estate distributions efficiently, though this does not replace professional advice on the IHT claim itself.

Planning for the Second Death: Will Structuring and Trusts

The TNRB is only valuable if the survivor’s estate actually benefits from it. A poorly drafted will can waste the allowance. For example, if the survivor leaves everything to a non-UK domiciled spouse who then moves abroad, the transferred NRB may be lost if the survivor’s estate is not subject to UK IHT at death.

A common strategy is the nil-rate band discretionary trust, where the first deceased’s NRB is “ring-fenced” into a trust rather than automatically passing to the survivor. This preserves the NRB for future generations while still allowing the survivor to benefit from the trust assets. However, this trust structure has become less popular since the introduction of the RNRB, as the trust may disqualify the estate from claiming the RNRB on the survivor’s death.

For most couples, a simple will leaving everything to the survivor is sufficient, provided the executor files the TNRB claim. The key is to review the will every five years and after any significant life event, such as the purchase of a new home or a change in the value of investment portfolios.

FAQ

Q1: Can I claim the transferable nil-rate band if my spouse died more than 10 years ago?

Yes, you can make a late claim, but HMRC requires a reasonable explanation for the delay. Accepted reasons include ignorance of the relief or the original executor’s failure to file. The claim is made on form IHT402 at the time of the survivor’s death, and HMRC will assess each case individually. Approximately 8% of TNRB claims are made more than four years after the first death, according to HMRC internal data (2023). The survivor’s executor must provide full details of the first estate, including assets, liabilities, and any chargeable transfers.

Q2: Does the transferable nil-rate band apply if the first spouse was not UK-domiciled?

Yes, provided the first spouse was domiciled in the UK for IHT purposes at the time of death. If the first spouse was non-UK domiciled but elected to be treated as UK-domiciled under the spouse exemption rules, the TNRB still applies. However, if the first spouse never established UK domicile and their estate was not subject to UK IHT, no transfer is available. The survivor’s domicile at the second death also matters—if the survivor has lost UK domicile, the transferred NRB may still be claimed against UK-situs assets, but the rules are complex and require professional analysis.

Q3: What happens if the first estate used part of the nil-rate band for a chargeable gift?

The unused percentage is calculated after accounting for any chargeable transfers made by the first spouse in the seven years before death. For example, if the first spouse made a gift of £50,000 to a child (exceeding the annual exemption), that £50,000 reduces the NRB used, leaving £275,000 unused (84.6%). That percentage transfers to the survivor. Lifetime gifts that are exempt (e.g., to a spouse or charity) do not reduce the unused portion. Executors must reconstruct the gift history accurately, as HMRC may request supporting documentation.

References

  • HM Revenue & Customs 2024, Inheritance Tax Statistics: 2023-24 Data Tables
  • HM Revenue & Customs 2023, IHT Manual: Transferable Nil Rate Band (IHTM43001-IHTM43080)
  • Office for Budget Responsibility 2024, Fiscal Risks Report: Inheritance Tax Receipts and Allowances
  • Law Commission 2023, Making a Will: Modernising the Law of Inheritance
  • Unilink Education 2024, Cross-Border Estate Planning Database (UK-IHT Module)