Transferable Nil-Rate Band Inheritance Tax UK: How Couples Can Double the IHT Threshold (2026)
The transferable nil-rate band (s8A IHTA 1984) allows a surviving spouse to claim the unused NRB from the first death — potentially doubling the IHT-free amount to £650,000. Add transferred RNRB (s8G) and the combined threshold for a couple passing the home to children reaches £1,000,000. It is NOT automatic — claim it on form IHT402, supported by evidence of the first marriage and estate.
| Scenario | Own NRB | Transferred NRB | RNRB (both) | Total Threshold |
|---|---|---|---|---|
| Single person (no home to children) | £325,000 | — | — | £325,000 |
| Single person + home to children | £325,000 | — | £175,000 | £500,000 |
| Survivor (first spouse used NRB fully) | £325,000 | £0 (0% unused) | £175,000 each | £500,000 (own only) |
| Survivor (first spouse: 50% NRB unused) | £325,000 | £162,500 (50%) | £350,000 (both) | £837,500 |
| Survivor (first spouse: 100% NRB unused) | £325,000 | £325,000 (100%) | — | £650,000 (no RNRB) |
| Survivor (100% NRB unused + home to children) | £325,000 | £325,000 (100%) | £350,000 (both) | £1,000,000 |
| Survivor with 2 predeceased spouses (cap applies) | £325,000 | £325,000 (capped at 100%) | £350,000 (both) | £1,000,000 |
2026/27. NRB: £325,000. RNRB: £175,000. Both frozen to 2030. RNRB tapers £1 per £2 above £2m estate on second death (fully lost at £2.7m couple). Transferred NRB: claim form IHT402 with IHT400 on second death. Transferred RNRB: claim form IHT436. Neither is automatic — evidence required.
Transferable Nil-Rate Band: Complete Guide
How the transferable nil-rate band works — the s8A IHTA 1984 mechanism
The transferable nil-rate band was introduced by the Finance Act 2008 with effect from 9 October 2007. Before this date, the standard IHT planning tool to use both spouses' NRBs was the NRB discretionary will trust — because the NRB could not simply transfer between spouses. Section 8A IHTA 1984 changed this fundamentally. The mechanism: (1) The first spouse dies. If their estate is below the NRB (e.g., everything passed to the surviving spouse under the spousal exemption — s18 IHTA 1984), 100% of their NRB was unused at the time of death; (2) The percentage of unused NRB is recorded — not the monetary amount. Example: if the NRB was £250,000 at the first death and the full £250,000 was unused, this is recorded as 100% unused; (3) On the surviving spouse's death: the percentage of unused NRB is applied to the NRB in force at the date of the survivor's death. In 2026/27 the NRB is £325,000. So 100% transferred × £325,000 = £325,000 additional NRB; (4) Total NRB on the second death = survivor's own NRB (£325,000) + transferred NRB (£325,000) = £650,000. This means the NRB at the second death benefits from the NRB freeze increase — if the NRB had risen (e.g., to £500,000), the transferred amount would be 100% × £500,000 = £500,000, not the £250,000 original. The NRB has been frozen at £325,000 since 2009 and is currently frozen to 2030.
The transferred RNRB — s8G IHTA 1984
The Residence Nil-Rate Band (RNRB) has its own transferability provisions under s8G IHTA 1984 (introduced alongside the RNRB in April 2017). The transferred RNRB works on the same percentage basis as the transferred NRB: (1) First spouse dies and leaves the home to the survivor (or the home is jointly owned — the survivor takes it by survivorship). No RNRB was used on the first death (either because the home passed to the spouse directly, or because the estate was below the NRB); (2) 100% of the RNRB is unused on the first death — this is recorded as 100%; (3) On the surviving spouse's death: 100% × RNRB at second death = £175,000 transferred RNRB (2026/27). Survivor's own RNRB: £175,000. Total RNRB = £350,000; (4) Combined with the dual NRBs: £650,000 + £350,000 = £1,000,000 total IHT-free threshold for a married couple where the home passes to direct descendants. Conditions for the RNRB: the home (or a qualifying residential property previously owned by the survivor) must pass to direct descendants (children, stepchildren, grandchildren). If the survivor sold the home and downsized: the downsizing addition (s8FA IHTA 1984) may preserve the RNRB entitlement even if there is no home at the date of death.
The claim — form IHT402 and the evidence required
The transferred NRB is NOT automatic. It must be claimed on the second death as part of the IHT400 return. The claim is made on form IHT402 (Claim to transfer unused nil-rate band). The IHT436 form is for the transferred RNRB. Evidence required for the transferred NRB claim: (1) Death certificate of the predeceased spouse; (2) Marriage or civil partnership certificate proving the relationship; (3) Grant of probate or letters of administration for the first estate (if probate was obtained); (4) Details of the first estate showing the NRB was unused — the will of the predeceased spouse, or a letter from the administrator of the first estate confirming assets and how they were distributed; (5) If the first death occurred before October 2007 (before the transferred NRB was introduced): the claim can still be made — the rules apply retrospectively. Evidence from a death 30+ years ago may be harder to locate. Key documents to keep: marriage certificate; both wills; both death certificates. Store these with the survivor's will so the personal representatives on the second death can find them quickly. Without adequate evidence, HMRC may reject the transferred NRB claim or require extensive investigation — potentially causing the estate to pay IHT that was not due.
Partial NRB transfer — where the first estate was partially taxable
The transferred NRB is only the UNUSED percentage of the NRB on the first death. Where the first estate used part of the NRB, only the unused portion transfers. Example: the first spouse died with a taxable estate of £100,000 (after spousal exemption) — this used £100,000 / £325,000 = 30.77% of the NRB. The unused percentage = 100% − 30.77% = 69.23%. Transferred NRB on second death = 69.23% × £325,000 = £225,000 (not the full £325,000). Where the first estate paid IHT in full (the entire NRB and more was used), the unused NRB percentage is 0% — nothing transfers. Scenarios where partial transfer applies: (1) The first spouse left some assets to children directly in the will (using part of the NRB), with the remainder to the survivor; (2) The first spouse made gifts in the 7 years before death that are added to the estate and use up part of the NRB; (3) The first estate was above the NRB even after spousal transfers — unlikely for large estates but possible. For claims involving partial transfer, the calculation must be presented clearly on IHT402 with supporting evidence of the first estate's composition.
Multiple predeceased spouses — the 100% cap
A person who has been widowed more than once may in principle claim transferred NRBs from multiple predeceased spouses. However, the total transferred NRB is capped at 100% of the NRB in force at the date of the final surviving spouse's death. Example: person A married B (B died, leaving 50% NRB unused). A then married C (C died, leaving 80% NRB unused). Total: 50% + 80% = 130% — but capped at 100%. On A's death: transferred NRB = 100% × £325,000 = £325,000 (not 130% × £325,000). The same cap applies to the RNRB (s8G IHTA): maximum transferred RNRB = 100% of one RNRB. In practice, where successive marriages each left most of the NRB unused, the claim is simply presented at the cap of 100% and the evidence for each previous marriage is included on the IHT402. Important: each transferred NRB claim requires evidence from the relevant prior marriage and estate — personal representatives must locate documents from potentially multiple prior deaths.
Frequently Asked Questions
What is the transferable nil-rate band for inheritance tax?
The transferable nil-rate band (s8A IHTA 1984) allows the unused percentage of a deceased spouse's NRB to transfer to the surviving spouse's estate. If the first spouse leaves everything to the survivor (using the spousal exemption — s18 IHTA), 100% of their NRB is unused. On the second death, the estate claims 100% × current NRB (£325,000 in 2026/27) = £325,000 additional NRB. Combined with the survivor's own NRB (£325,000), the total is £650,000. Add transferred RNRB (£350,000) if the home passes to direct descendants: total threshold = £1,000,000.
Is the transferred nil-rate band automatic?
No — the transferred NRB is not automatic. It must be claimed on form IHT402 as part of the IHT400 return on the second death. Evidence required: first death certificate, marriage certificate, and details showing the first estate's NRB was unused (first spouse's will, probate documents from first death). Similarly, the transferred RNRB (s8G IHTA 1984) must be claimed on form IHT436. Without a claim supported by evidence, the transfer does not apply — the estate pays IHT without the additional threshold.
How much is the transferable nil-rate band for married couples in 2026?
In 2026/27: surviving spouse's own NRB = £325,000. Transferred NRB (100% where nothing used on first death) = £325,000. Total NRB = £650,000. Add both RNRBs if the home passes to direct descendants: transferred RNRB (100%) = £175,000 + survivor's own RNRB £175,000 = £350,000. Combined IHT-free threshold for a married couple with the home passing to children = £1,000,000. This assumes 100% of both NRBs and both RNRBs were unused on the first death, and the estate on the second death is below £2m (above which the RNRB tapers).
Can the transferred nil-rate band be claimed if the first spouse died before 2007?
Yes — the transferred NRB (introduced by Finance Act 2008 with effect from 9 October 2007) can be claimed even where the first spouse died before 2007, or many decades earlier. The claim uses the percentage of the NRB that was unused on the first death, applied to the NRB in force on the second death. Evidence from a death 30+ years ago may be harder to find (old probate records, wills, death certificates) but the claim is available. HMRC will require evidence regardless of how long ago the first death occurred.
What happens if the first spouse used some of their NRB?
Only the unused percentage of the NRB transfers. Example: first spouse died with a taxable estate of £65,000 (after spousal transfers), using 20% of the NRB (£65,000 / £325,000). The unused percentage = 80%. Transferred NRB on second death = 80% × £325,000 (current NRB) = £260,000 (not the full £325,000). If the first estate was fully above the NRB and paid full IHT, nothing transfers. The claim must show the first estate composition — the percentage calculation is presented on form IHT402 with supporting evidence.
Preserve the Evidence — Keep Marriage and Probate Documents Safe
Without evidence of the first spouse's unused NRB, the transferred threshold cannot be claimed. Store marriage certificates, both wills, and first death probate documents with the survivor's will. A WillSafe will kit includes guidance on what to keep and where to store it.
View Will Kits from £39.99