To claim the transferable nil rate band, the personal representatives of the second spouse or civil partner to die submit form IHT402 to HMRC alongside form IHT400. The claim transfers the percentage of the nil rate band left unused on the first death, applied to the band in force at the second death. It must reach HMRC within 24 months of the end of the month in which the survivor died.
This guide sets out the process for England and Wales: when the form is needed, when it is not, how the transfer is calculated, and the mistakes that most often delay a claim. Figures are current as at August 2026 and are subject to change.
What is the transferable nil rate band, and what does IHT402 do?
The transferable nil rate band lets a surviving spouse or civil partner add their late partner's unused nil rate band to their own. Form IHT402 is the schedule that makes the claim. It records what percentage of the nil rate band was unused on the first death, so HMRC can apply that percentage to the survivor's estate at their later death.
The nil rate band is the amount that can pass free of inheritance tax, £325,000 as at August 2026, frozen until 5 April 2031 following the extension announced at the Budget on 26 November 2025 (gov.uk, subject to change). Anything above the available band is taxed at 40%, or 36% where at least 10% of the net estate passes to charity.
The transfer exists because gifts between spouses and civil partners are usually exempt. Many people leave everything to their partner, so none of the first band is used, and all of it can carry forward. You can read how this fits the wider picture in our guide to inheritance tax in England and Wales.
Do you always need to file IHT402?
No. Since 1 January 2022, many estates that transfer the whole of a first spouse's nil rate band no longer complete form IHT400 or IHT402 at all. Where 100% of the first band is available and the survivor's estate qualifies as an excepted estate, the figures are given on the probate application instead of a full account.
An estate can be an excepted estate on this basis where its gross value is no more than £650,000, the entire unused nil rate band of one predeceased spouse or civil partner is being transferred, and the usual excepted-estate conditions are met (gov.uk, report an excepted estate, as at August 2026, subject to change). The old form IHT217 that used to claim the transfer in these cases was withdrawn for deaths on or after that date.
- File IHT400 and IHT402 where inheritance tax is due, where only part of the first band transfers, or where the estate is too large to be excepted.
- Skip the full account where 100% transfers, the estate is within £650,000, and it otherwise qualifies as excepted. You claim on the probate application.
Claiming only a partial percentage removes the £650,000 route, and the personal representatives must then complete the full account with IHT402 attached.
How to claim the transferable nil rate band with IHT402
Where a full account is needed, the personal representatives of the survivor's estate make the claim by completing IHT402 and sending it with form IHT400. The form is only used after the second death, not on the first. Work through these steps.
- Confirm the estate qualifies. The person who has now died must have had a spouse or civil partner who died before them, and some of that first person's nil rate band must be unused. The first death can be at any time, though the calculation differs for deaths before 1975.
- Trace who dealt with the first estate. Identify the executor or administrator of the first death, as you may need figures and documents from that estate to complete the form.
- Gather the supporting documents. You will usually need the first person's death certificate, their will (or a note that there was none), any grant of representation, and any deed of variation that changed who inherited.
- Work out the unused percentage. Establish the nil rate band at the first death, deduct anything that used it up (chargeable legacies and gifts in the seven years before that death), and express the remainder as a percentage.
- Complete form IHT402. Enter the details of the person who has now died, the first spouse or civil partner, the value of the first estate, and the figures that establish the unused percentage.
- Send it with IHT400. IHT402 is a schedule to the main account. Submit the two together to HMRC, not separately, along with any other schedules the estate needs.
Download the current form from the gov.uk IHT402 page. If the estate involves probate, our guide to what probate is and how it works explains where this fits in the wider administration.
How the transfer is calculated: the percentage rule
The transfer works on a percentage, not a fixed cash amount. HMRC takes the proportion of the nil rate band left unused on the first death and applies it to the band in force when the survivor dies. Because the band can rise over time, an old unused allowance can be worth more today than it was then.
The formula is: unused band at first death, divided by the nil rate band at first death, multiplied by 100, then applied to the current band. The uplift is capped so the survivor's own band can never be increased by more than 100%, however many previous spouses or civil partners there were.
IHT402 or IHT436: which form transfers which band?
IHT402 transfers only the standard nil rate band. If a home is passing to children or grandchildren and you also want the first person's unused residence nil rate band, that is a separate claim on form IHT436. Estates that need both must file both, each attached to IHT400.
| Feature | IHT402 | IHT436 |
|---|---|---|
| Band transferred | Nil rate band (£325,000) | Residence nil rate band (up to £175,000) |
| When it applies | First spouse or civil partner died first with unused nil rate band | Claiming unused residence band where a home passes to direct descendants |
| Attaches to | Form IHT400 | Form IHT400, alongside IHT435 |
| Basis of transfer | Percentage of unused nil rate band | Percentage of unused residence nil rate band |
| Deadline | 24 months from end of month of second death | 24 months from end of month of second death |
Sources: gov.uk IHT402 and gov.uk IHT435 and IHT436, as at August 2026, subject to change. The residence band of up to £175,000 can lift a couple's total tax-free amount to £1,000,000 where a home passes to descendants, and it tapers away by £1 for every £2 of estate above £2,000,000.
The 24-month deadline and provisional claims
A claim on IHT402 must reach HMRC within 24 months of the end of the month in which the survivor died. Miss it, and the transfer can be lost, although HMRC has discretion to accept a late claim in limited circumstances. The main account, IHT400, is separately due within 12 months of death, and any tax is due by the end of the sixth month after death.
Where the deadline is close and the first-death paperwork is proving hard to find, HMRC may accept a provisional claim. The personal representatives give their best estimate of the unused percentage and confirm the figures once the evidence is available.
- IHT402 claim: within 24 months of the end of the month of the second death.
- IHT400 account: within 12 months of the death.
- Inheritance tax payment: by the end of the sixth month after the month of death.
What people get wrong in practice
Most refused or delayed transfers come down to a handful of avoidable errors, and each one is easy to prevent. The transfer is valuable, often a second £325,000 of tax-free estate as at August 2026, so the personal representatives should check the percentage, the gifts before the first death, and the paperwork before submitting IHT402. The five below are the ones that recur.
- Assuming it is automatic. HMRC does not apply the transfer on its own. Without a claim on IHT402 or on the probate application, the extra band is simply not given.
- Using a cash figure instead of a percentage. The claim is a percentage of the first band, not the pounds unused at the time. Recording £150,000 rather than the percentage understates the uplift when bands have risen.
- Forgetting gifts before the first death. Chargeable gifts made in the seven years before the first death reduce the unused band, and leaving them out overstates the claim.
- Missing IHT436 for the home. IHT402 does not carry the residence band. Where a property passes to descendants, a separate IHT436 claim is needed as well.
- Losing the first-death records. If the will, grant or account cannot be found, HMRC will often accept alternative evidence, such as a statutory declaration from someone who knew the estate, rather than reject the claim outright.
Where an estate is close to the thresholds, or a first death happened decades ago, many families take advice before filing. Careful record-keeping now also makes a future claim far simpler, a point worth building into any estate plan.
Frequently asked questions
These are the questions personal representatives most often ask when claiming the transferable nil rate band on form IHT402. The short answers below cover whether the transfer is automatic, how IHT402 differs from IHT436, who qualifies, when the form is due, and where to download it, all current as at August 2026 and subject to change.
Is the transferable nil rate band applied automatically?
No. The transfer must be claimed. For most estates that means completing form IHT402 and sending it with form IHT400. Where the whole band transfers and the estate is excepted, the claim is made instead on the probate application. If no claim is made, HMRC does not add the extra band, and the transfer can be lost after the deadline.
What is the difference between form IHT402 and form IHT436?
Form IHT402 transfers the unused standard nil rate band, up to £325,000. Form IHT436 transfers the unused residence nil rate band, up to £175,000, which applies only where a home passes to children or other direct descendants. An estate that needs both must complete both, each as a schedule to form IHT400.
Can unmarried partners transfer an unused nil rate band?
No. The transferable nil rate band is only available between married couples and registered civil partners. Cohabiting partners, however long they have been together, cannot pass an unused nil rate band to each other, which is one reason careful estate planning often matters more, not less, for unmarried couples.
When does form IHT402 need to reach HMRC?
Within 24 months of the end of the month in which the survivor died. HMRC can accept a late claim in limited circumstances, and may allow a provisional claim where the supporting documents are hard to obtain before the deadline. The main IHT400 account is due within 12 months of the death.
Can you transfer more than one spouse's nil rate band?
Yes, if someone was widowed more than once, unused bands from more than one late spouse or civil partner can be claimed. The total uplift to the survivor's own band is capped at 100%, so the most anyone can inherit in transferred allowance is one extra full nil rate band.
Where do you download form IHT402?
From gov.uk, on the page titled Inheritance Tax: claim to transfer unused nil rate band (IHT402). Always use the current version, as HMRC updates the form and the guidance notes from time to time.