Does the transfer apply?
Were you married to, or in a civil partnership with, the person who died?
Cohabiting couples — however long together — do not qualify for the TNRB. The law requires a legal marriage or registered civil partnership.
Did your spouse or civil partner die before you?
The TNRB applies when the first of two spouses dies. It is claimed when the survivor's estate is assessed for IHT on the second death.
On their death, did they leave most or all of their estate to you (or to charity)?
Transfers between UK-domiciled spouses and transfers to charity are IHT-exempt and leave the NRB unused. If they left significant assets to others — children, siblings — those may have used part of the NRB and the transfer will be smaller.
What it's worth
If the entire first NRB was unused — typical where everything passed to the surviving spouse
Your own £325k + the transferred £325k from your late spouse, before the estate is taxed
40% of £325,000 — the maximum tax saving compared to an estate with a single nil-rate band
From the end of the month of the second death. Miss it and HMRC may refuse the claim
Four steps to the transfer
You need: death certificate (first death), marriage or civil partnership certificate, and the first deceased's will or grant of probate. These prove the legal relationship and show how much of the NRB was used.
Divide the unused NRB at first death by the NRB in force at that time. What transfers is a percentage, not a fixed sum — so a 1995 death with an unused NRB of £154,000 transfers 100%, not £154,000, and is applied to the current £325,000.
Where families lose the transfer
The transferable amount is a percentage of the NRB in force when the first spouse died — not today's £325,000. If the first death was in 2005 (NRB: £275,000), 100% transfers as a percentage, then applies to £325,000. Using the wrong threshold mis-states the transfer amount on IHT402.
HMRC has discretion to accept late claims but routinely refuses them without good reason. The clock starts from the end of the month of the second death, not the date you first think about it. Personal representatives dealing with a complex estate can miss this without realising.
The residence nil-rate band (£175,000) has its own transferable equivalent — it is not claimed on IHT402. If the first deceased owned a home that qualified, a separate claim on IHT436 (filed alongside IHT435 and the IHT400) may transfer up to £175,000 of additional RNRB, adding a further £70,000 of potential IHT saving.
Gifts to children, siblings, or others on the first death use the NRB. If the first deceased left £100,000 to children and £225,000 unused, only the unused 69.2% transfers. Many families claim 100% incorrectly because they assume everything went to the survivor — they need to check the first will and grant.
Transferable NRB — questions, answered.
The transferable nil-rate band is one part of the wider spouse exemption system. The IHT Spouse Exemption Brief covers the unlimited spousal exemption (everything you leave a UK-domiciled spouse is IHT-free), the transferable NRB calculation, and the residence nil-rate band on the second death — all in one document.
Read the spouse IHT brief — freeLibrary
Free guides behind Transferable NRB
These free briefs explain the rules and planning implications in full.
The IHT completion product builds on this explanation — with your estate's figures, your asset values, and the forms that actually apply.
Read the guideThe IHT completion product applies the spousal exemption and TNRB calculation to your specific estate — so box 116 on the IHT400 is correct.
Read the guideThe IHT400 guided completion product walks through every section in sequence — with your estate's figures already in place where the records allow.
Read the guideThe Executor's First Hour extends this guide with the estate's specific accounts, authorities, and documents — so the transition has a clear map.
Read the guideAll guides are available free from the Valoren library — no account required.