Losing a spouse or civil partner is difficult enough without also facing HMRC paperwork. If your loved one has died and their spouse or civil partner passed away earlier without using their full Inheritance Tax allowance you could be entitled to claim extra tax free allowance through form IHT402.
This guide explains what the form covers who is eligible to make a claim and how to complete it correctly the first time so your family does not miss out on a valuable tax saving during probate.
What Is IHT402 and Why It Matters
IHT402 is the HMRC form used to claim the Transferable Nil Rate Band (TNRB) once someone has died. It gives the personal representative of an estate the ability to move any unused Inheritance Tax (IHT) threshold from a deceased spouse or civil partner across to the estate of the second person to pass away. When the first spouse leaves most or all of their estate to the survivor their own Nil Rate Band often goes largely unused. That unused portion is not lost. It can be claimed and added to the second estate’s threshold.
This matters because the outcome can be significant. Inheritance Tax is charged at 40 percent on anything above the available threshold so a missed claim can cost a family a substantial sum. HMRC will not apply this transfer on its own. It has to be requested through IHT402 with proper supporting evidence from the first death.
Many families end up paying more Inheritance Tax than necessary simply because this form was overlooked or executors assumed the allowance transferred automatically. Knowing about IHT402 early in the probate process helps prevent this avoidable loss.
What Is the Transferable Nil Rate Band?
The Nil Rate Band (NRB) is the amount an estate can be worth before Inheritance Tax applies. It currently stands at £325,000 per person and has been frozen at this level since 2009. When a married person or civil partner dies and leaves some or all of their estate to their surviving spouse the transfer is usually exempt from IHT. This means part or all of their NRB goes unused.
The Transferable Nil Rate Band allows that unused percentage to pass to the surviving spouse. When the second person dies their estate can benefit from both their own NRB and the transferred portion from their late spouse. In theory this means a married couple could pass on up to £650,000 tax free before even factoring in the Residence Nil Rate Band (RNRB) which adds a further £175,000 per person where a home is left to direct descendants.
| Allowance | Amount per person | Combined for a couple |
| Nil Rate Band (NRB) | £325,000 | up to £650,000 |
| Residence Nil Rate Band (RNRB) | £175,000 | up to £350,000 |
| Maximum combined | £500,000 | up to £1,000,000 |
Rates and thresholds are set by HMRC and can change. Always check gov.uk or speak with a tax adviser to confirm current figures before submitting a claim.
Who Is Eligible to Claim TNRB
Not every estate qualifies for this transfer. Eligibility depends on a few specific conditions rather than simply being a surviving spouse or civil partner. You can generally claim the Transferable Nil Rate Band if all of the following apply:
- The first spouse or civil partner died on or after 13 November 1974
- Part or all of their Nil Rate Band was unused at the time of their death
- The surviving spouse or civil partner has now also died
- You are the personal representative or executor responsible for the second estate
- Proper records exist showing how much of the first Nil Rate Band remained unused
If the first spouse died before 1974, different transfer rules may apply, and it is worth seeking professional advice before proceeding with a claim. Civil partnerships are treated exactly the same as marriages for this purpose, no matter when the partnership was formally registered.
It is also worth noting that eligibility is not affected by remarriage. If the surviving spouse later remarries and their new spouse also dies, the estate may potentially claim NRB from more than one previous marriage subject to the overall cap.
When You Need to Submit IHT402
You need to complete IHT402 when you are claiming unused Nil Rate Band from a previously deceased spouse or civil partner as part of the full Inheritance Tax account for the second estate. This form is required whenever the estate does not qualify as an excepted estate, meaning its value exceeds the relevant thresholds or it includes assets such as trusts, foreign property, or gifts that call for a fuller declaration to HMRC.
IHT402 is never submitted on its own. It must accompany form IHT400 as part of the complete Inheritance Tax account for the estate. HMRC uses the figures provided on IHT402 to work out exactly how much additional Nil Rate Band the second estate is entitled to claim based on the percentage that remained unused after the first death.
If the estate falls below the expected estate thresholds, a different and simpler process usually applies instead using form IHT217. Knowing which route your estate falls into early on helps avoid submitting the wrong paperwork and prevents unnecessary delays during probate.
Documents and Information You’ll Need
Before starting the form gather the following information to avoid unnecessary delays. Having everything ready in advance makes the process considerably smoother and reduces back and forth with HMRC:
- The full name and date of death of the first spouse or civil partner
- A copy of the grant of probate or confirmation for the first estate if one was issued
- Details of the value of the first estate at the time of death
- Any gifts made by the first spouse in the seven years before their death
- Details of any exemptions or reliefs claimed on the first estate such as spouse exemption or business relief
- The marriage or civil partnership certificate showing the date the relationship began
If the first death happened many years ago, some of these records may be difficult to trace, especially if paperwork was lost or the solicitor involved is no longer practising. HMRC does allow reasonable estimates in these situations but wherever possible supporting evidence should be provided. Stronger documentation reduces the likelihood of HMRC sending query letters, which can otherwise slow down the entire probate process considerably.
Step-by-Step Guide to Completing IHT402
Filling in IHT402 is straightforward once you understand what each section asks for.
- Confirm eligibility, check that the first spouse’s NRB was not fully used and that you are the correct person to make the claim
- Gather the first estate’s figures, work out the total value of the first estate and how much of it was chargeable to IHT
- Calculate the unused percentage, divide the unused NRB by the NRB rate that applied at the time of the first death
- Complete the personal details sections, enter names, dates and marriage or civil partnership information exactly as they appear on official certificates
- Declare gifts and exemptions, list any lifetime gifts or reliefs that affected the first estate’s NRB usage
- Attach supporting documents, include probate copies, certificates and any HMRC correspondence from the first death
- Submit with IHT400, send IHT402 together with the main account form, not separately
- Keep copies, retain a full copy of everything submitted in case HMRC requests clarification
Double check every figure before sending. A small error in the unused percentage can change the tax outcome significantly and may trigger a longer review from HMRC.
IHT402 Deadlines You Cannot Miss
Timing matters when claiming the Transferable Nil Rate Band. The claim must generally be made within 24 months from the end of the month in which the second spouse or civil partner died. Missing this window does not always mean the claim is lost but it does make the process more complicated and less certain.
In some cases, HMRC allows a longer period, particularly where there is a reasonable excuse for the delay such as difficulty tracing records from the first death or genuine uncertainty over who the correct personal representative is. Each case is assessed individually so there is no guarantee an extension will be granted.
If probate has already been granted for the second estate and the claim was not included at the time, you can often still submit a late claim in many circumstances. That said, acting quickly remains the safest approach. Gathering historic records, especially from decades ago, takes time and any delay in submitting IHT402 can hold up the wider probate process, leaving beneficiaries waiting longer than necessary to receive their inheritance.
IHT402 vs IHT217: Choosing the Right Form
People often confuse IHT402 with IHT217 since both deal with transferring unused nil rate bands. The difference comes down to the type of estate involved.
| Feature | IHT402 | IHT217 |
| Used with | IHT400 (full account) | Excepted estate probate application |
| Estate complexity | Higher value or complex estates | Simpler estates below excepted thresholds |
| Claim detail required | Detailed calculation of unused NRB | Simplified declaration |
| Submission method | Alongside full IHT account | With probate application forms |
If you are unsure which category your estate falls into, a solicitor or probate specialist can confirm this quickly and it will save time filling in the wrong paperwork.
Common Errors That Delay or Reject Claims
Even straightforward claims can get held up over mistakes that are entirely avoidable with careful preparation. Watch out for these common issues:
- Submitting IHT402 without the required IHT400 account attached
- Miscalculating the unused percentage carried forward from the first estate
- Missing or mismatched names and dates between certificates and the form itself
- Forgetting to include lifetime gifts that reduced the first spouse’s Nil Rate Band
- Failing to attach evidence of the earlier grant of probate or confirmation
- Assuming the transfer applies automatically without submitting any form at all
HMRC will not apply the Transferable Nil Rate Band on its own accord. The claim must be actively made and properly evidenced with supporting documentation or the second estate simply loses out on a valuable tax saving that it was otherwise entitled to.
Even small inconsistencies such as a misspelled name or a mismatched date of birth can trigger a query from HMRC and add weeks to the process. Taking time to double check every detail before submission is one of the simplest ways to keep a claim moving smoothly.
Potential Inheritance Tax Savings With TNRB
The financial impact of a successful TNRB claim can be substantial, and this is often where families realise just how important the paperwork really is. Inheritance Tax is charged at 40 percent on the value of an estate above the available threshold. If a fully unused Nil Rate Band transfers across, that means an extra £325,000 becomes tax-free, which works out to a potential saving of up to £130,000 in tax for the estate.
Combined with the Residence Nil Rate Band, which applies where a home passes to children or grandchildren, the total tax-free allowance for a married couple can reach as much as £1,000,000. For many families this is the difference between a manageable tax bill and one that forces the sale of a family home to cover the debt.
This is exactly why executors should never overlook this claim when eligibility applies. A single form, correctly completed, can preserve a substantial part of the estate for beneficiaries rather than handing it over in tax that was never legally due. Rates and thresholds should always be confirmed with HMRC before finalising any figures.
Final Thoughts
Claiming the Transferable Nil Rate Band through form IHT402 is one of the most effective ways to reduce Inheritance Tax on a family estate yet it remains one of the most overlooked steps in probate. The process demands accurate historic records, careful calculation and attention to HMRC deadlines but the potential saving of up to £130,000 or more makes the effort worthwhile. If any part of the process feels unclear, working with a probate solicitor or tax adviser can help ensure the claim is accurate, complete and submitted on time.
This article provides general information only and is not a substitute for professional legal or tax advice. Inheritance Tax rules and thresholds can change so always confirm current figures on gov.uk or with a qualified adviser before making a claim.
FAQs
What Is Form IHT402 Used For?
IHT402 is used to claim the unused Nil Rate Band from a deceased spouse or civil partner and transfer it to the estate of the second person to die.
Do I Need To Submit Iht402 With Every Estate?
No. It is only required when claiming the Transferable Nil Rate Band as part of a full IHT400 account for the second death.
What Is The Current Nil Rate Band Amount?
The standard Nil Rate Band is £325,000 per person, though this figure is set by HMRC and should be confirmed before submitting a claim.
Can I Claim TNRB If The First Spouse Died Decades Ago?
Yes, as long as they died on or after 13 November 1974 and part of their NRB was unused at the time.
What Happens If I Miss The Deadline For Iht402?
Late claims may still be accepted if there is a reasonable excuse for the delay, though it is safer to submit within 24 months of the end of the month of death.
Is The Transferable Nil Rate Band Automatic?
No. It must be actively claimed using IHT402 and proper evidence or the estate will not receive the additional allowance.
What Is The Difference Between Iht402 And Iht217?
IHT402 applies to full IHT400 accounts for more complex estates while IHT217 applies to simpler excepted estates during probate.
Can Civil Partners Claim The Transferable Nil Rate Band?
Yes. Civil partners are treated the same as married couples for the purpose of this claim.
How Much Tax Could A Successful Claim Save?
A fully unused NRB transfer can save up to £130,000 in Inheritance Tax since the tax rate above the threshold is 40 percent.
Who Should Complete Iht402?
The personal representative or executor of the second estate is responsible for completing and submitting the form along with the main IHT400 account.
