Transferable Nil Rate Band: how unused Inheritance Tax allowance transfers between spouses

The Transferable Nil Rate Band allows unused Inheritance Tax (IHT) allowances from a deceased spouse or civil partner to be transferred to the surviving partner’s estate. This can increase the amount that can pass on free from Inheritance Tax when the surviving spouse or civil partner later dies.

Many married couples and civil partners do not use their full Nil Rate Band when the first person dies because assets often pass directly to the surviving spouse. As transfers between spouses and civil partners are generally exempt from Inheritance Tax, the first estate may have little or no tax liability.

Where unused allowances remain, the surviving spouse’s executors can usually claim the additional allowance when the second death occurs. If the claim is not made correctly, the estate may pay more Inheritance Tax than necessary.

This guide explains how the Inheritance Tax transferable nil rate band works, how to transfer unused Nil Rate Band, the process for making a claim and the key records needed to support the application. This allowance sits within the wider tax planning framework explained in our ultimate guide to personal tax in the UK.

What is the Transferable Nil Rate Band?

The Transferable Nil Rate Band allows unused percentage of a deceased person’s standard Inheritance Tax allowance to be transferred to their surviving spouse or civil partner.

The Nil Rate Band is the amount that can generally pass free from Inheritance Tax before any tax becomes payable. Where the first spouse or civil partner does not use all of their available allowance, the unused proportion can potentially be transferred.

The transferred allowance is not a separate allowance created at the first death. Instead, it increases the amount available to the surviving spouse or civil partner’s estate when they later die. This mechanism is one of several ways inheritance and tax rules work together to reduce the overall burden on a family across two deaths rather than one.

The transfer is calculated as a percentage of the unused allowance rather than simply transferring a fixed cash amount.

How Nil Rate Band transfer between spouses works

The most common situation where a transfer is available is when the first spouse or civil partner leaves their estate to the survivor.

For example:

• A husband dies and leaves his estate to his wife.
• The spouse exemption means there is usually no immediate Inheritance Tax charge.
• His Nil Rate Band remains unused.
• When the wife later dies, her executors can claim the unused percentage from her husband’s estate.

This means the surviving spouse’s estate may benefit from both their own available Nil Rate Band and the unused percentage transferred from their late spouse or civil partner.

The same principles apply to civil partners.

Why unused Nil Rate Band is often available

Before transferable allowances were introduced, families could lose unused Inheritance Tax allowances where assets passed directly to a surviving spouse.

The introduction of the transfer rules helped prevent this problem.

In many estates, the first spouse’s Nil Rate Band remains unused because:

• The estate passes entirely to the surviving spouse.
• The value of the estate is below the available allowance.
• Assets are transferred in a way that qualifies for an exemption.

As a result, many surviving spouses or civil partners can potentially claim additional allowance when their own estate is eventually administered.

How much Inheritance Tax allowance can be transferred?

The amount transferred depends on the percentage of the first spouse’s allowance that was unused.

For example:

• If the first spouse used none of their Nil Rate Band, 100% of the unused allowance may be available for transfer.
• If the first spouse used 25% of their allowance, the remaining unused percentage may be transferred.

The calculation is based on the proportion unused at the first death rather than simply the cash value of the allowance at that time.

This percentage-based approach is important because Inheritance Tax thresholds can change between the first and second death.

How to transfer unused Nil Rate Band after death

The transfer does not happen automatically.

When the surviving spouse or civil partner dies, their executors or personal representatives must make a claim to HMRC for the unused allowance. HMRC’s transferable Nil Rate Band claim guidance explains how personal representatives make the formal claim and the supporting documents that may be required.

The claim is normally submitted as part of the Inheritance Tax administration process for the second estate.

The executors need to demonstrate:

• That the deceased was married or in a civil partnership.
• The date of the first spouse or civil partner’s death.
• How much of the first allowance was unused.
• That the surviving spouse’s estate is entitled to claim the transfer.

Documents needed to claim the transfer

Keeping records from the first estate is extremely important because the claim may not be made until many years later.

Useful documents can include:

• The first spouse or civil partner’s death certificate.
• The will of the first person to die.
• Grant of probate documentation.
• Estate valuation details.
• Inheritance Tax forms submitted at the first death, where applicable.
• Details of assets passing to the surviving spouse.

Missing records can make it more difficult for executors to prove the available transferable allowance when the second estate is administered. This ties closely into valuing an estate for IHT purposes generally, since the first estate’s valuation directly supports the transfer claim on the second.

Can Nil Rate Band transfer apply if the first spouse died years ago?

Yes. A claim for transferable Nil Rate Band may still be possible even where the first spouse or civil partner died many years earlier.

The rules allow unused allowances from deaths that occurred before the introduction of transferable allowances to be considered, provided the relevant conditions are met.

However, executors may need to obtain historical information about the earlier estate to support the claim.

This is why retaining estate documents after the first death can be valuable for future generations.

Transferable Nil Rate Band and the Residence Nil Rate Band

The Transferable Nil Rate Band should be distinguished from the Residence Nil Rate Band (RNRB).

The standard Nil Rate Band relates to the general Inheritance Tax threshold available against an estate.

The Residence Nil Rate Band is a separate allowance linked to qualifying residential property passing to direct descendants. Because eligibility depends on the specific beneficiary and property involved, it’s worth checking who can claim the IHT residence nil rate band separately from the standard transfer claim.

Both allowances may potentially transfer between spouses and civil partners, but they have different eligibility rules and claim requirements.

For example, an estate may qualify for transferable Nil Rate Band but fail to qualify for transferred Residence Nil Rate Band if the conditions relating to the family home and direct descendants are not satisfied.

Worked example: transferring unused Nil Rate Band

John dies leaving his entire estate to his wife, Sarah.

Because the transfer qualifies for the spouse exemption, no Inheritance Tax is payable on John’s estate and his Nil Rate Band remains unused.

Several years later, Sarah dies and leaves her estate to their children.

Sarah’s executors review John’s estate records and submit a claim for his unused allowance.

As John’s Nil Rate Band was not used, Sarah’s estate can potentially claim the unused percentage in addition to her own available allowance.

This reduces the part of Sarah’s estate that may be subject to Inheritance Tax.

Common mistakes when claiming Inheritance Tax allowance transfer

Common errors include:

• Assuming the unused allowance transfers automatically.
• Failing to keep records from the first spouse’s estate.
• Confusing Nil Rate Band transfer with Residence Nil Rate Band transfer.
• Not checking whether the first spouse used any of their allowance.
• Submitting incomplete information to HMRC.
• Waiting until late in the estate administration process to investigate the available allowance.

This confusion is understandable given how closely the Inheritance Tax thresholds and the RNRB interact, but the two allowances have genuinely separate rules and should be claimed independently.

These mistakes can result in delays or a higher Inheritance Tax liability than necessary.

Planning for future Nil Rate Band transfer claims

Good estate planning involves more than preparing a will. Families should also consider how future executors will prove eligibility for transferable allowances.

Practical steps include:

• Keeping copies of previous estate documents.
• Recording how assets passed on the first death.
• Reviewing wills after major family or financial changes.
• Maintaining clear records of property ownership and gifts.

These steps can make the administration of the second estate significantly easier. It’s also worth reviewing the current Inheritance Tax thresholds periodically, since these figures determine how much of any unused allowance is actually worth claiming.

Key takeaways

The Transferable Nil Rate Band allows unused Inheritance Tax allowances from a deceased spouse or civil partner to be used by the surviving partner’s estate.

The transfer can significantly increase the amount that passes free from Inheritance Tax, but it must be claimed and supported with appropriate evidence.

Understanding how to transfer unused Nil Rate Band, keeping historic estate records and distinguishing between standard Nil Rate Band and other allowances can help families ensure the correct Inheritance Tax allowance transfer is claimed when it is needed.