IHT435 Form UK: Claiming the Residence Nil Rate Band on Second Death

Updated: 13 June 2026 • Reading time: 9 min • By WillSafe UK Editorial Team

The residence nil rate band (RNRB) is worth up to £175,000 of additional inheritance tax threshold — and up to £350,000 on second death if the transferred RNRB from a pre-deceased spouse is also claimed. But the allowance is not automatic: it must be actively claimed by submitting form IHT435 (and, where applicable, IHT436) alongside the IHT400 account. Failure to submit these forms means the RNRB is simply foregone. This guide explains what IHT435 and IHT436 are, when they are needed, how to complete them, and how to avoid the most common errors.

IHT435: Claiming the RNRB on the Current Death

Form IHT435 (“Claim for residence nil rate band (RNRB)”) is submitted as a supplementary schedule to the IHT400 when you are claiming the RNRB for the current deceased’s estate. The conditions for the RNRB are:

1. The deceased was domiciled in the UK at the date of death.
2. The estate includes a qualifying residential interest— broadly, a residential property (or a share of one) that the deceased owned and occupied as their residence at some point during ownership. Holiday homes not used as a main residence may not qualify.
3. The residential property “closely inherits”— that is, it passes directly to a lineal descendant (child, grandchild, step-child etc.) or to a trust meeting the qualifying conditions (an immediate post-death interest for a lineal descendant, or a bare trust for a minor descendant).
4. The estate’s net value does not exceed £2m, or if it does, the RNRB is tapered at £1 for every £2 above £2m (and is nil once the estate reaches £2.35m, or £2.7m if the transferred RNRB is also available).

IHT435 walks through each condition step by step and calculates the available RNRB for the estate. If none of the RNRB is available (for example, because the property passes into a discretionary trust), IHT435 still records the unused RNRB percentage, which can then be transferred to a surviving spouse via IHT436 on the survivor’s later death.

IHT436: Transferring the Unused RNRB from a Pre-deceased Spouse

Form IHT436 (“Claim to transfer any unused residence nil rate band”) is submitted when the current deceased had a pre-deceased spouse or civil partner who did not use all of their RNRB. The unused percentage is transferred to the current estate and added to the current deceased’s own RNRB.

The key feature of the transfer rules is that if the first spouse died before 6 April 2017— when the RNRB was introduced — HMRC treats them as having had a full, 100% unused RNRB. This means that on the survivor’s death the estate can claim:

• The survivor’s own RNRB: £175,000 (2026–27)
• The transferred RNRB from the pre-deceased spouse: 100% × £175,000 = £175,000
• Total: £350,000 additional threshold for the family home

Combined with the transferable nil-rate band (up to £650,000 on second death), the total IHT threshold on second death can reach £1m for a qualifying estate, before the taper applies.

What Information Do You Need to Complete IHT435 and IHT436?

For IHT435, you will need:

• Details of every residential property owned by the deceased at death (address, value, ownership share, whether occupied as residence)
• Details of how each property passes under the will or intestacy and to whom
• Whether any property sold after 8 July 2015 triggers the downsizing addition (if so, the sale date, proceeds, and details of how the proceeds passed)
• The net value of the estate (to check the £2m taper)

For IHT436, you will need:

• Full name and date of death of the pre-deceased spouse or civil partner
• Their National Insurance number (if known)
• Value of their estate at death
• Whether any RNRB was claimed on their death and how much was used
• Whether the downsizing rules applied to the pre-deceased spouse’s estate
• Evidence of the marriage or civil partnership (marriage certificate or civil partnership certificate)

Where the pre-deceased spouse died before 2017, you do not need to show they had an unused RNRB — the 100% transfer is deemed automatically. But you still need to complete IHT436 to make the claim formally.

The Downsizing Addition: Preserving the RNRB After Moving

If the deceased sold a property after 8 July 2015 and moved to a smaller (or less valuable) home — or moved into care and no longer owned a property — the “downsizing addition” may preserve part or all of the RNRB that would otherwise be lost. The conditions are:

• The sold (or former) property would have qualified as a qualifying residential interest if still owned at death
• At least some of the assets in the estate pass to direct descendants (they do not have to be the proceeds of the sale specifically)
• The current estate has a qualifying residential interest worth less than the full RNRB, or no qualifying residential interest at all

The downsizing addition makes up the gap between the value of the current residential interest and the full RNRB, up to a cap. It is claimed in IHT435. Where the pre-deceased spouse also had a downsizing addition, this feeds into IHT436 for the transferred RNRB calculation.

Common Mistakes When Claiming the RNRB

Step-by-Step: How to Submit IHT435 and IHT436

1. Confirm RNRB conditions are met— check the deceased owned a qualifying residential interest, that it passes to a direct descendant, and that the estate net value is below or near £2m.
2. Check for transferred RNRB— was the deceased ever married or in a civil partnership with a pre-deceased partner? If so, IHT436 will likely be needed.
3. Check for downsizing addition— did the deceased sell or move from a former property after 8 July 2015? Gather the sale documents and asset trail.
4. Complete IHT435— using the form guidance (IHT435 Notes available from HMRC’s website). Calculate the RNRB applicable and the unused percentage.
5. Complete IHT436 if applicable— gather evidence of the pre-deceased spouse’s death and estate. Calculate the transferable unused RNRB percentage.
6. Attach both forms to the IHT400— submit all forms together to HMRC’s Inheritance Tax office in Nottingham. Incomplete submissions delay processing.

Frequently Asked Questions