Form IHT402: Claiming a Deceased Spouse's Unused Nil Rate Band — Worked Example
Form IHT402 is the HMRC schedule you submit with the IHT400 to transfer the unused part of a previously deceased spouse's or civil partner's nil rate band to the estate of the second person to die. The transfer is recorded as a percentage, not a cash figure — and where the first spouse left everything to the survivor, that percentage is the full 100%, doubling the available threshold from £325,000 to £650,000.
The most valuable thing the IHT402 does is rescue a tax-free allowance that would otherwise have been wasted. When most or all of an estate passes to a surviving spouse, those assets are exempt from Inheritance Tax — which means the first person's nil rate band (NRB) sits unused. HMRC lets you carry that unused percentage forward and apply it on the second death. But it does not happen automatically: someone has to make the claim, and that claim is form IHT402.
This guide walks the form box by box, with two worked examples — a clean 100% transfer and a trickier partial transfer — and shows exactly where the result lands on the IHT400. All figures are checked against the current HMRC form (version HMRC 04/25) and the official GOV.UK IHT402 page.
The basic nil rate band is £325,000 and the standard Inheritance Tax rate is 40% on the value of an estate above the available threshold. These are frozen at these levels for several years. A surviving spouse who inherits a full unused band can therefore have up to £650,000 of basic NRB before the residence nil rate band is even considered. Source: GOV.UK — Inheritance Tax.
When you use IHT402 (and when you don't)
The form's own front page sets out four conditions — all must be true:
- the person who has died now (the "deceased") died on or after 9 October 2007;
- their spouse or civil partner died before them;
- when that spouse or civil partner died, their estate did not use up all of the nil rate band available to it; and
- you want to transfer the unused amount to the deceased's estate.
If the second estate is small enough that a full IHT400 is not required, you may instead use the shorter IHT217 (for excepted estates) — but that only works for a 100% transfer. Any partial transfer, or any case already on the IHT400 route, uses IHT402.
Which boxes record the first spouse's death and the unused percentage
The IHT402 is laid out in five labelled sections. Here is what each numbered box is asking for, grouped by the job it does.
| Box | What it captures | Where the figure comes from |
|---|---|---|
| 1–5 | First spouse's title and name, date of death, last permanent address, and date and place of marriage / civil partnership | Death certificate, marriage or civil partnership certificate |
| 6 | Did the first spouse leave a will? (Yes — enclose a copy) | The will and any codicils |
| 7 | Net value of the first estate passing under the will or intestacy | Grant of representation, or add assets and deduct liabilities |
| 8 | Was a grant of representation (confirmation in Scotland) obtained? | Grant — or death certificate if no grant was taken out |
| 9 | The nil rate band in force at the first death | IHT400 "Rates and tables" (e.g. £325,000 since 6 April 2009) |
| 10 | Chargeable gifts/transfers in the 7 years before the first death | Records of lifetime gifts |
| 11 | NRB available against the first estate (box 9 − box 10) | Calculated |
| 12 | Residence nil rate band (RNRB) used (deaths on/after 6 Apr 2017) | Lower of home value passing to descendants and the year's max RNRB |
| 13–16 | Legacies/assets, jointly owned share, trust assets and gifts-with-reservation passing on the first death — excluding anything that passed to the now-deceased | Will, intestacy rules, joint ownership records |
| 17 | Total chargeable estate of the first spouse (boxes 13 + 14 + 15 + 16) | Calculated |
| 18 | NRB available for transfer (box 11 + box 12 − box 17), capped at the basic NRB at the first death | Calculated |
| 19 | The unused percentage — box 18 ÷ box 9 × 100, to 4 decimal places, not rounded up, never more than 100% | Calculated |
| 20 | NRB at the date of the second (now) death | IHT400 "Rates and tables" (£325,000 in 2026) |
| 21 | Transferable nil rate band — box 20 × box 19 percentage, rounded up to the nearest pound | Calculated |
So the two boxes that carry the heart of the claim are box 19 (the percentage that travels between the two deaths) and box 21 (that percentage turned into a cash figure using the threshold at the second death). Everything above box 19 exists only to work out that percentage; everything below it converts the percentage to money.
Harold and Margaret Whitcombe — the clean 100% transfer.
Harold died in March 2018, leaving his entire estate to his wife Margaret. Because spouse transfers are exempt, none of Harold's nil rate band was used. Margaret died on 12 February 2026, leaving an estate worth £590,000 to their two children. Their daughter, acting as executor, completes IHT402 alongside the IHT400.
- Box 9 — NRB in force when Harold died (2018): £325,000
- Box 10 — chargeable gifts in his last 7 years: £0
- Box 11 — NRB available (box 9 − box 10): £325,000
- Box 17 — total chargeable estate (everything went to Margaret, exempt): £0
- Box 18 — NRB available for transfer (£325,000 + £0 − £0): £325,000
- Box 19 — £325,000 ÷ £325,000 × 100 = 100.0000%
- Box 20 — NRB at Margaret's death (2026): £325,000
- Box 21 — £325,000 × 100.0000% = £325,000 transferred
Margaret's estate now has £325,000 (her own) + £325,000 (transferred) = £650,000 of basic nil rate band. Her £590,000 estate sits entirely under that £650,000, so the Inheritance Tax due is £0. Without the IHT402 claim, £265,000 would have been taxed at 40% — a bill of £106,000 that the form makes disappear.
Calculating a partial transfer when some NRB was used on the first death
The clean case above is the common one, but plenty of first spouses left a slice of their estate to children, grandchildren or others before passing the rest to the survivor. Those non-spouse gifts use up part of the first nil rate band, so less than 100% transfers. The mechanics are identical — the percentage in box 19 just comes out lower.
Sunita and Raj Mehta — the partial transfer.
Raj died in 2011, when the nil rate band was already £325,000. His will left a £130,000 legacy to his brother and the remainder of his estate to his wife Sunita. The £130,000 to his brother is a chargeable legacy that bites into Raj's nil rate band; everything passing to Sunita is spouse-exempt. Sunita died in 2026.
- Box 9 — NRB when Raj died (2011): £325,000
- Box 13 — legacy to his brother (passing to a non-spouse): £130,000
- Box 17 — total chargeable estate: £130,000
- Box 18 — NRB available for transfer (£325,000 − £130,000): £195,000
- Box 19 — £195,000 ÷ £325,000 × 100 = 60.0000%
- Box 20 — NRB at Sunita's death (2026): £325,000
- Box 21 — £325,000 × 60.0000% = £195,000 transferred
Sunita's estate gets her own £325,000 plus £195,000 transferred = £520,000 of basic nil rate band. The percentage — not the original cash amount — is what carries forward, which is why a band only 60% used in 2011 still delivers 60% of today's £325,000.
This is the subtlety people miss. If Raj had used £130,000 of a £325,000 band, you might think £195,000 of cash transfers. It is really 60% of whatever the band is at the second death. Had the band risen to £400,000 by Sunita's death, the transfer would have been £240,000, not £195,000. The percentage protects the survivor from being frozen at old, lower thresholds — and HMRC's instruction is explicit: in box 19, use 4 decimal places and do not round up, because rounding the percentage up could overstate the transfer.
What counts as "using up" the band
Boxes 13 to 16 only include value that was chargeable — that is, after exemptions and reliefs, and excluding anything that passed to the survivor (who is the person who has now died). So in the Mehta example you do not list the assets Sunita inherited; you list only the £130,000 that went elsewhere. Charitable legacies, agricultural and business property relief, and the spouse exemption itself all reduce the chargeable figure and therefore preserve band for transfer. Where you have applied any relief other than spouse exemption, list it in box 22.
Supporting documents HMRC wants
The form is explicit that you must send photocopies of the following with your IHT402 — taken from the estate of the first spouse to die:
| Document | When it is required |
|---|---|
| A copy of the grant of representation (confirmation in Scotland) to the first estate | If a grant was taken out for the first death |
| A copy of the death certificate | If no grant was taken out (e.g. a small estate that passed wholly to the survivor) |
| A copy of the will (and any codicils) | If the first spouse left a will |
| A copy of any deed of variation or similar instrument | If the people who inherited the first estate were changed after death |
If records have been lost, HMRC expects you to make full enquiries — the solicitor who acted, the original executors, family members. You can order copies of grants and wills (England and Wales) via the official search for probate records service, and death, marriage and civil partnership certificates from the General Register Office.
You must send IHT402 no later than 24 months after the end of the month in which the second person died. For a death on 12 February 2026, the form is due by 28 February 2028. Miss it and HMRC can refuse the transfer — turning a £0 bill into a six-figure one.
Where the transferred percentage feeds the IHT400 calculation
IHT402 is a schedule — it never stands alone. The figure you have worked out flows into the main IHT400 in two places:
- On the IHT400 itself, you tick that you are claiming a transfer of unused nil rate band and attach the completed IHT402.
- When you reach the tax calculation (the IHT400 Calculation page, form IHT400 Calculation), the nil rate band available to the second estate is increased by the box 19 percentage. In practice you take the standard £325,000 and add the transferred band from box 21, giving the total tax-free threshold the calculation then subtracts before applying 40%.
In the Whitcombe example, the IHT400 Calculation starts from £325,000, adds the £325,000 from box 21, reaches a £650,000 threshold, and — because the estate is £590,000 — produces a tax figure of nil. The IHT402's entire purpose is to lift that threshold line on the IHT400.
The basic nil rate band transferred via IHT402 is separate from the residence nil rate band (RNRB), which can add up to £175,000 where a home passes to direct descendants, lifting a couple's combined potential to £1 million. An unused RNRB from the first death is claimed on a different form — IHT436 — not IHT402. Keep the two claims distinct; box 12 on IHT402 only records RNRB used at the first death for the basic-band maths. See GOV.UK — Residence nil rate band.
- IHT402 transfers a deceased spouse's unused nil rate band as a percentage, claimed on the second death — it is never automatic.
- Box 19 holds the unused percentage (box 18 ÷ box 9 × 100, four decimals, no rounding up); box 21 converts it to cash using the second-death threshold.
- A first spouse who left everything to the survivor passes 100% — turning £325,000 into £650,000 of basic band.
- Partial transfers come from non-spouse legacies; the percentage — not the old cash figure — carries forward, so the survivor benefits from today's threshold.
- Send photocopies of the grant (or death certificate), will, and any deed of variation from the first death, within 24 months of the second death.
- The result lifts the nil rate band on the IHT400 Calculation; the residence nil rate band is a separate claim on IHT436.
Frequently asked questions
Can I claim my spouse's nil rate band even if they died decades ago?
Yes. There is no limit on how long ago the first death occurred — the transfer is claimed on the second death, regardless of when the first spouse died (the rules even cover Estate Duty and Capital Transfer Tax eras). The only deadline that matters is the 24-month window after the second death.
What if I remarried — can I claim from more than one deceased spouse?
You can claim from more than one previously deceased spouse or civil partner, but the total uplift to your own nil rate band is capped at 100% — that is, a maximum of one additional full band (£325,000 on today's figures). You cannot stack three full bands.
How do I find the nil rate band in force when my spouse died?
Use the "Rates and tables" section published with the IHT400, or the historical NRB list on GOV.UK. The band has been £325,000 since 6 April 2009; before that it stepped up over the years (for example £312,000 in 2008–09). Enter the correct historic figure in box 9 — getting it wrong skews the box 19 percentage.
Is the transferred band a fixed cash amount or a percentage?
A percentage. Box 19 records the unused percentage; box 21 applies it to the threshold at the second death. This means if thresholds rise between the two deaths, the survivor benefits from the higher figure — you are not locked to the old cash amount.
Do I still file IHT402 if no tax is due?
If the estate needs the transferred band to avoid tax, yes — you must make the claim so HMRC recognises the higher threshold. For very small (excepted) estates needing only a straightforward 100% transfer, the shorter IHT217 may be used instead. If the estate is comfortably under £325,000 on its own, no transfer claim is needed at all.
What documents will HMRC reject the claim without?
The grant of representation (or, if none was taken out, the death certificate), a copy of the will, and a copy of any deed of variation that changed who inherited the first estate. HMRC asks for photocopies, not originals, sent with the form.
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Sources: GOV.UK — IHT402 form and notes (HMRC 04/25) · GOV.UK — Inheritance Tax (£325,000 nil rate band, 40% rate) · GOV.UK — Residence nil rate band. Form box numbers verified against the official IHT402 PDF dated April 2025.