Married couples and civil partners can transfer unused nil-rate band between estates — effectively doubling the tax-free IHT threshold to £650,000. But it is not automatic: executors must actively claim it.
£325,000
Standard NRB (Each)
Each individual's nil-rate band — frozen since 2009.
£650,000
Combined NRB (Couples)
Transferable nil-rate band doubles the tax-free threshold for surviving spouses.
£175,000
RNRB (Each)
Residence Nil-Rate Band — also transferable between spouses.
£1,000,000
Maximum Combined
Couples leaving their home to direct descendants can shelter up to £1 million.
Every individual has a nil-rate band (NRB) — the amount of their estate that is free from Inheritance Tax. In 2024/25, this is £325,000. Anything above this threshold is taxed at 40%.
When the first spouse or civil partner dies, their nil-rate band may be wholly or partly unused — for example, because they left everything to the surviving spouse under the spousal exemption. Under the Finance Act 2008, this unused allowance does not disappear. Instead, it is transferred to the surviving spouse's estate and can be claimed on the second death.
The transferred allowance is expressed as a percentage of the nil-rate band at the time of the first death. That percentage is then applied to the nil-rate band in force at the time of the second death. If the nil-rate band has increased between the two deaths, the surviving spouse benefits from the higher amount.
It Is Not Automatic — You Must Claim It
The transferable nil-rate band is not applied automatically. Executors of the second spouse's estate must actively claim it by submitting forms IHT400 and IHT402 to HMRC within 24 months of the second death. Failing to claim it means paying IHT that could have been avoided.
When the first spouse dies, their nil-rate band (£325,000) may be wholly or partly unused — for example, because they left everything to the surviving spouse under the spousal exemption. The unused percentage is recorded and carried forward.
The transferable nil-rate band is expressed as a percentage of the nil-rate band at the time of the first death. If 100% was unused, 100% is transferred. If 50% was used (e.g. £162,500 left to children), 50% is transferred.
The transferred percentage is applied to the nil-rate band in force at the time of the second death — not the first. If the nil-rate band has increased between the two deaths, the surviving spouse benefits from the higher amount.
The transferable nil-rate band is not automatic. Executors of the second spouse's estate must actively claim it by submitting forms IHT400 and IHT402 to HMRC, along with supporting documents. The claim must be made within 24 months of the second death.
The Residence Nil-Rate Band (RNRB) of up to £175,000 — which applies when leaving a main home to direct descendants — is also transferable between spouses in the same way. This allows couples to shelter up to £1 million from IHT.
Executors of the second spouse's estate must follow this process to claim the transferable nil-rate band.
You will need the marriage certificate, the first spouse's will, the grant of probate or letters of administration, and any IHT return submitted on the first death.
Work out what percentage of the nil-rate band was unused on the first death. If the first spouse left everything to the survivor, 100% was unused. If they left £162,500 to children, 50% was unused.
Form IHT400 is the main Inheritance Tax return for the second estate. It must be completed in full, including all assets, liabilities, and reliefs claimed.
Form IHT402 is the specific form for claiming the transferable nil-rate band. It requires details of the first spouse's estate and the unused nil-rate band percentage.
The claim must be submitted to HMRC within 24 months of the end of the month in which the second spouse died. Late claims may be refused.
If the main residence is being left to direct descendants, the transferable Residence Nil-Rate Band is claimed on form IHT435. This is a separate claim from the transferable nil-rate band.
Potentially Exempt Transfers (PETs) — lifetime gifts made within seven years of the first death — reduce the available nil-rate band and therefore the amount that can be transferred. The table below illustrates the impact.
| Scenario | NRB Used | NRB Unused | Amount Transferred |
|---|---|---|---|
| No lifetime gifts made | £0 | £325,000 (100%) | 100% — full £325,000 transferred |
| Gifts of £100,000 made within 7 years | £100,000 | £225,000 (69.2%) | 69.2% — £225,000 transferred |
| Gifts of £325,000 made within 7 years | £325,000 | £0 (0%) | 0% — nothing transferred |
| Left £162,500 to children in will | £162,500 | £162,500 (50%) | 50% — £162,500 transferred |
These are the most common errors that result in executors failing to claim the full transferable nil-rate band.
Executors of the second estate need the first spouse's will, grant of probate, and IHT return. If these documents are lost, the claim becomes significantly more difficult.
The claim must be made within 24 months of the second death. HMRC has discretion to accept late claims in exceptional circumstances, but this is not guaranteed.
Potentially Exempt Transfers (PETs) made within seven years of the first death reduce the available nil-rate band — and therefore the amount that can be transferred.
The transferable nil-rate band is not applied automatically. Executors must actively claim it on form IHT402. Failing to claim it means paying IHT that could have been avoided.
The Residence Nil-Rate Band is also transferable — but it must be claimed separately on form IHT435. Many executors claim the transferable NRB but forget the transferable RNRB.
If the first spouse's will left everything to the survivor — using the full spousal exemption — the nil-rate band is technically unused and can be transferred. However, if the will left assets to children that exceeded the nil-rate band, the transfer is reduced.
A Deed of Variation allows beneficiaries to redirect their inheritance within two years of the first death. For example, if the first spouse left £500,000 to the survivor, a Deed of Variation could redirect £325,000 to the children — using the nil-rate band immediately and reducing the estate on the second death.
Deeds of Variation are a powerful post-death planning tool, but they require careful advice to ensure they achieve the intended tax saving without unintended consequences.
Related Guides
Spousal Exemption & IHT
How the unlimited spousal exemption works and why it creates unused nil-rate band.
Protective Property Trusts
Use your nil-rate band on first death while protecting the family home.
Residential Nil Rate Band
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Inheritance Tax Explained
Who pays IHT, how it is calculated, and strategies to reduce the bill.
Deed of Variation
Redirect inheritance within two years of death to optimise tax relief.
Seven-Year Rule for Gifting
How lifetime gifts affect the nil-rate band and IHT planning.
The transferable nil rate band allows the unused Inheritance Tax allowance (nil-rate band) from the first spouse's estate to be transferred to the surviving spouse's estate. This effectively doubles the tax-free threshold from £325,000 to £650,000 on the second death.
No. The transferable nil rate band is not applied automatically. Executors of the second spouse's estate must actively claim it by submitting forms IHT400 and IHT402 to HMRC, along with supporting documents. Failing to claim it means paying IHT that could have been avoided.
The claim must be submitted to HMRC within 24 months of the end of the month in which the second spouse died. HMRC has discretion to accept late claims in exceptional circumstances, but this cannot be relied upon.
Executors will need the marriage certificate, the first spouse's will, the grant of probate or letters of administration from the first death, and any IHT return submitted on the first death. Form IHT402 must be completed and submitted with form IHT400.
Yes, but lifetime gifts (Potentially Exempt Transfers) made within seven years of the first death reduce the available nil-rate band — and therefore the amount that can be transferred. If the first spouse made gifts totalling £325,000 within seven years of death, nothing is available to transfer.
Yes. The Residence Nil-Rate Band (RNRB) of up to £175,000 is also transferable between spouses. It must be claimed separately on form IHT435. Combined with the transferable standard nil-rate band, couples can shelter up to £1 million from IHT.
Yes. There is no time limit on how long ago the first spouse died — the 24-month deadline runs from the second death, not the first. However, the older the first death, the harder it may be to locate the necessary documents.
Yes. Civil partners have exactly the same rights as married couples in relation to the transferable nil-rate band and the transferable Residence Nil-Rate Band.
If the first spouse was previously married and their first spouse also died with an unused nil-rate band, the surviving spouse can potentially claim multiple transferred nil-rate bands — but the total cannot exceed 100% of the nil-rate band in force at the second death.
Yes. A Deed of Variation allows beneficiaries to redirect their inheritance within two years of the first death. This can be used to direct assets up to the nil-rate band to children rather than the surviving spouse — using the nil-rate band immediately and reducing the estate on the second death.
The transferable nil-rate band can save tens of thousands of pounds in Inheritance Tax — but only if it is claimed correctly and on time. Our wills and estate planning solicitors in Chester can guide executors through the process.
Spousal Exemption & IHT
How the unlimited spousal exemption works and why it creates unused nil-rate band.
Protective Property Trusts
Use your nil-rate band on first death while protecting the family home.
Inheritance Tax Planning
Strategies to reduce your IHT bill — from lifetime gifting to trusts and reliefs.
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