Inheritance Tax When the Second Parent Dies
Combining both parents' nil-rate and residence bands can shelter up to £1,000,000 before Inheritance Tax is due — a worked example of the transferable-allowance claim.
The short answer
When the second parent dies, their estate can claim both parents' unused nil-rate bands and both parents' unused residence nil-rate bands — up to £1,000,000 tax-free before 40% applies, provided the first parent left everything to the survivor and the family home passes to children or grandchildren. Nothing about this happens automatically: the executor has to claim it.
Why the first death usually triggers no tax at all
On the first parent's death, gov.uk confirms an unlimited exemption for what passes to a spouse or civil partner: there is normally no Inheritance Tax due on anything “you leave… to your spouse, civil partner, a charity or a community amateur sports club.” Most married couples leave everything to each other, so the first death is usually tax-free regardless of the estate's size — and, critically, the first parent's own £325,000 nil-rate band and £175,000 residence band go completely unused.
The transferable allowance, on gov.uk's own wording
Those unused bands aren't lost. gov.uk: “If you're married or in a civil partnership and your estate is worth less than your threshold, any unused threshold can be added to your partner's threshold when you die.” The same transfer principle extends to the residence nil-rate band, via HMRC's separate RNRB guidance. In the simplest case — the first parent left 100% to the survivor, using 0% of either band — the second parent's estate can claim 100% of the first parent's unused bands on top of their own.
Worked example
A father dies first in 2019, leaving his entire estate to his wife. He uses none of his £325,000 nil-rate band and none of his £175,000 residence band (his estate qualified for the spouse exemption in full). His widow dies in 2026/27, leaving an estate worth £920,000, including the family home worth £400,000, to their two children.
| Step | Figure |
|---|---|
| Her own nil-rate band | £325,000 |
| Her late husband's transferred (unused) nil-rate band | £325,000 |
| Her own residence nil-rate band (home to children) | £175,000 |
| Her late husband's transferred (unused) residence band | £175,000 |
| Total tax-free threshold available | £1,000,000 |
| Her net estate | £920,000 |
| Inheritance Tax due | £0 — estate is below the combined threshold |
Because the combined threshold (£1,000,000) exceeds the estate (£920,000), no Inheritance Tax is due at all on the second death, despite the estate being nearly three times the ordinary £325,000 nil-rate band on its own. Had the couple never claimed the transfer, the widow's estate would have had only her own £500,000 to work with, leaving £420,000 exposed to tax at 40%.
What the executor actually has to do
The transfer is not applied by HMRC automatically — the second parent's personal representatives must claim it as part of reporting the estate, using the percentage of each band the first parent left unused (not necessarily 100%, if the first parent made some taxable gifts or left specific legacies to someone other than the spouse). Getting the first parent's paperwork — will, grant of probate, any earlier IHT forms — is the practical first step, and can be the hardest part if those records are years or decades old.
What can reduce the claim below 100%
- The first parent left some of the estate to someone other than the spouse — a legacy to children, a trust, or a charity on the first death uses up some of the nil-rate band, reducing what's available to transfer.
- The home didn't pass to the first parent's spouse at all — the residence nil-rate band transfer follows its own separate unused-percentage calculation from HMRC's RNRB guidance.
- The first parent's own estate was taxed in full at some point (for instance a second marriage where only part of the estate passed to this particular spouse) — only the genuinely unused percentage carries forward.
If a rental property is in the mix
A buy-to-let in either parent's estate is valued and counted the same as any other asset — it gets no special relief and doesn't itself help or hurt the residence nil-rate band claim (that band only concerns the home lived in, not lettings). See our guide to Inheritance Tax on rental property if the estate includes buy-to-lets alongside the family home.
This is a guide, not financial, tax or legal advice. Figures are estimates from the published rates and thresholds, which change with each Budget. Your own position depends on facts a guide can't see — check anything that matters against gov.uk guidance or a qualified adviser before you act on it.
gov.uk: Inheritance Tax (transferable nil-rate band) · HMRC: residence nil-rate band (transferable RNRB) · gov.uk: IHT thresholds and interest rates, all read verbatim 11 Sep 2026. Worked example figures are illustrative, not a real case; site/taxdata.py's IHT dataset supplies the thresholds and rates used.
Quick answers
Up to £1,000,000, if the first parent left everything to the surviving spouse (using none of their own nil-rate or residence bands) and the family home passes to children or grandchildren on the second death. The executor has to claim the transferred allowances — they aren't automatic.
You can, on the second parent's estate, if the first parent's £325,000 nil-rate band and £175,000 residence band went unused (typically because everything passed to the surviving spouse). The claim uses the exact unused percentage, which can be less than 100% if the first parent left legacies to anyone other than their spouse.
Evidence of the first parent's estate — their will (or intestacy position), grant of probate if one was needed, and any Inheritance Tax forms filed at the time — to establish what percentage of their nil-rate band and residence band went unused. HMRC's own claim process sets out the exact forms; gather this paperwork as early as possible since it can be decades old.
No. £1,000,000 is the maximum when both full nil-rate bands and both full residence bands are claimed and transferred — it requires the first parent to have used none of their own allowances, and the home to pass to direct descendants. Many estates qualify for less.
Sources
The primary documents this page is built from. Links checked 5 September 2026.
- Inheritance Tax — GOV.UK
- Inheritance Tax: passing on a home — GOV.UK
- Inheritance Tax: Residence Nil Rate Band — GOV.UK / HMRC
- Rates and allowances: Inheritance Tax thresholds and interest rates — GOV.UK / HMRC