Second death inheritance tax calculator
- For a married couple's estate passing to children
- Doubled nil-rate band up to £650,000
- Doubled residence band up to £350,000
- Handles a partly-used first allowance
- No sign-up required
Second death calculator
Work out the IHT when the surviving spouse dies and the estate passes to children. Nothing is stored or sent anywhere.
Estimate for the second death based on 2026/27 rates (nil-rate band £325,000, residence nil-rate band £175,000, both transferable; 40% standard rate, 36% with 10%+ to charity; £2m RNRB taper). Assumes the first estate passed to the survivor and the transferred percentage shown. It doesn't cover lifetime gifts, trusts, or business and agricultural relief. Not financial or legal advice. Source: HMRC.
How inheritance tax works on the second death
For most married couples, Inheritance Tax isn't a one-death event. It's a second-death event. When the first partner dies and leaves everything to the other, there's no IHT to pay, because transfers between spouses and civil partners are exempt with no limit. The tax question only arrives when the survivor dies and the estate finally passes to the children.
That's why searches like "inheritance tax calculator for second parent death" are so common. People handling a parent's estate have often already been through the first death years earlier, when nothing was due, and now need to work out what the children actually owe. The good news is that the first death, by using none of the allowances, doubles what's available now.
The doubling: how £1 million comes about
Each person has a £325,000 nil-rate band. When the first spouse dies leaving everything to the survivor, none of their band is used, so 100% of it transfers. The survivor's estate then has two nil-rate bands: £650,000. Add the residence nil-rate band, £175,000 each, doubled to £350,000 where a home passes to children, and the combined threshold reaches £1 million. Only the value above that faces the 40% charge.
| Allowance on second death | Amount |
|---|---|
| Own nil-rate band | £325,000 |
| Transferred nil-rate band | £325,000 |
| Own residence nil-rate band | £175,000 |
| Transferred residence nil-rate band | £175,000 |
| Combined threshold | £1,000,000 |
Worked example: £1.2 million estate
A widow dies leaving a £1.2 million estate, including the family home, to her two children. Her late husband left everything to her, so his allowances were unused and transfer in full.
| Step | Amount |
|---|---|
| Estate value | £1,200,000 |
| Nil-rate band (doubled) | -£650,000 |
| Residence nil-rate band (doubled) | -£350,000 |
| Taxable estate | £200,000 |
| IHT at 40% | £80,000 |
| Left to the children | £1,120,000 |
The children inherit £1,120,000 after an £80,000 bill. Had the couple not been married, or had the home gone to someone other than a direct descendant, the allowances would be far smaller and the tax much higher.
When only part of the first allowance transfers
The doubling assumes the first spouse left everything to the survivor. That's the usual arrangement, but not always the case. If the first spouse left some of their estate directly to the children, part of their nil-rate band was used, and only the unused percentage transfers.
Say the first spouse left £162,500 to the children on the first death. That's half the nil-rate band, so 50% is used and 50% transfers. The survivor's combined nil-rate band becomes £325,000 plus 50% of £325,000, which is £487,500, not £650,000. The calculator lets you enter this percentage, because it changes the answer significantly. The transfer is worked out as a percentage precisely so it keeps pace with the band even when it rises between the two deaths.
Widows and widowers: same rules
If you're a widow or widower working out your own position, this is exactly your situation. Your late spouse's allowances transfer to you, so your estate is assessed with the doubled bands. It applies even if your spouse died decades ago, and even if they died before the residence nil-rate band existed in 2017, because on that first death 100% of the (then unavailable) band counts as unused and transfers.
Claiming the transfer
The transferred allowances aren't given automatically. The executors of the second estate have to claim them, using form IHT402 for the nil-rate band and IHT436 for the residence nil-rate band, within two years of the end of the month of the second death. They'll need the first spouse's death certificate, will, and details of what passed on the first death. Miss the claim and the estate could pay tens of thousands more than it needs to.
To check the residence element in detail, including the value-of-home cap and the £2 million taper, use the residence nil-rate band calculator. For a single person or a first-death estate, the main inheritance tax calculator is the one to use.
Second death questions
How is IHT worked out on the second parent's death? The survivor's estate claims their own allowances plus the transferred bands from the first parent, up to £650,000 nil-rate band and £350,000 residence band, so a couple can pass up to £1 million to children before the 40% charge.
Why was there no tax on the first death? Everything left to a spouse is exempt from IHT, so no tax was due and none of the first allowances were used.
What if the first spouse used some of their allowance? Only the unused percentage transfers. Leaving half the band to children on the first death means the survivor's combined nil-rate band is £487,500, not £650,000.
Does this apply to a widow or widower? Yes. That's the second-death position, and it applies even if the first spouse died before 2017.