Farra is a death administration assistant for UK families. Get step-by-step guidance for registering a death, applying for probate, notifying banks, and managing bereavement admin. From essential documents to practical checklists, Farra simplifies estate paperwork and funeral-related tasks so you can focus on what matters.
IHT436 is the counterpart to IHT402: just as IHT402 transfers the unused standard nil rate band from a deceased spouse, IHT436 transfers the unused Residence Nil Rate Band. When both apply, a couple can potentially shelter up to £1,000,000 from inheritance tax entirely — but only if the conditions are met and both forms are correctly completed.
IHT436 is the supplementary schedule used to transfer the unused Residence Nil Rate Band (RNRB) from a first-deceased spouse or civil partner to the estate of the surviving partner. It is submitted alongside IHT435 (which claims the RNRB on the current estate) and the main IHT400.
The principle is the same as the transferable nil rate band (IHT402): allowances that were unused at the first death are not lost — they can be transferred and applied at the second death. This is sometimes called the transferable RNRB (TRNRB).
Like IHT402, the transfer is expressed as a percentageof the RNRB, not a fixed amount — and that percentage is applied to the RNRB in force at the second death.
You need to complete IHT436 when all of the following apply:
Critical point: IHT436 cannot be submitted alone. It is always an addition to IHT435. If the current estate does not qualify for the RNRB at all (for example, because there is no qualifying property), you cannot claim the transferred RNRB either — it can only be used to top up an existing IHT435 claim.
The RNRB was introduced on 6 April 2017. Before that date, it did not exist — so it was impossible for anyone to have used their RNRB.
The legislation addresses this elegantly: if the first spouse died before 6 April 2017, their RNRB is treated as 100% unused. The full RNRB available at the second death can therefore be transferred, regardless of what the first spouse owned, how their estate was distributed, or whether they owned a property at all.
This means that where the first spouse died any time before April 2017 — including decades ago — the surviving spouse's estate is entitled to claim 100% of the RNRB via IHT436, provided the other conditions for IHT435 are met.
Example: John died in 1995. His wife Mary dies in 2026 and qualifies for the RNRB on her estate. She can claim 100% of the £175,000 RNRB via IHT436 in addition to her own £175,000 RNRB via IHT435 — giving a combined RNRB of £350,000, despite the fact the RNRB did not exist when John died.
Where the first spouse died after 6 April 2017, you need to calculate what percentage of their RNRB was unused:
Susan died in 2020 when the RNRB was £175,000. She left her entire estate to her husband (spouse exemption applied), so she used no RNRB. Percentage unused: 100%. Her husband dies in 2026 when the RNRB is £175,000. Transferable RNRB = 100% × £175,000 = £175,000.
Peter died in 2019 when the RNRB was £150,000. He left a property worth £90,000 to his children (using £90,000 of RNRB) and the rest to his wife. Percentage unused: (£150,000 − £90,000) ÷ £150,000 = 40%. His wife dies in 2026 when the RNRB is £175,000. Transferable RNRB = 40% × £175,000 = £70,000.
Completing these forms yourself?
1 in 3 applications are sent back for form errors. In 2 minutes, we'll check the fields people most often get wrong — before you submit.
To support the IHT436 claim, you will need:
The £2 million taper that applies to the RNRB (see the IHT435 guide) applies to the combined RNRB — own RNRB plus transferred RNRB from IHT436. There is no relaxation of the taper threshold because a transferable RNRB is being claimed.
For a couple claiming both their RNRBs (total RNRB of £350,000), the taper means:
Note: The taper withdrawal rate of £1 per £2 above £2 million applies to the total RNRB available. For a couple with a combined RNRB of £350,000, full withdrawal occurs at a net estate of £2,700,000 (£2m + 2 × £350,000).
Where both the standard NRB and the RNRB are being transferred from a first deceased spouse, you submit IHT402 (for the NRB transfer) and IHT436 (for the RNRB transfer) alongside the IHT400 and IHT435. These are separate forms for separate allowances and must both be completed. Together, they can give a combined tax-free allowance of up to £1,000,000: two NRBs (£650,000) plus two RNRBs (£350,000).
1 in 3 probate applications are sent back. The most common reason: errors on exactly these forms.
Answer 5 questions in under 2 minutes. We'll tell you which forms apply to your estate, what goes in the fields people most often get wrong, and check your answers before you submit.
Free to check · 2 minutes · No account needed · £179 for your full probate pack
Related guides