Inheritance Tax grossing up calculator
Source: gov.uk (2025-03-05)

Use this calculator to gross up an estate, when the will leaves ‘free of tax’ gifts and the residue is partly or completely exempt from Inheritance Tax.

When someone dies, they can leave gifts in their will ‘free of tax’. This does not mean there’s no Inheritance Tax to pay.

It means the person receiving the gift gets the full amount stated. If any Inheritance Tax is due, it’s taken from the rest of the estate (the residue).

Grossing up is the process of working out how much of the estate is liable for Inheritance Tax. It’s needed when both:
- someone that’s liable for Inheritance Tax (a chargeable beneficiary) is left a ‘free of tax’ gift in the will
- the residue is partly or completely exempt from Inheritance Tax
When to use

You can use the calculator for:
- simple grossing up — where all gifts are ‘free of tax’ and the residue is completely exempt
- four-stage grossing up — where some gifts are ‘free of tax’ and some are not, or all gifts are ‘free of tax’ and the residue is partly exempt
In some situations, grossing up is more complicated. Do not use the calculator if either of these apply:
- Successive charges relief (https://www.gov.uk/hmrc-internal-manuals/inheritance-tax-manual/ihtm22041) (also called quick succession relief) — where Inheritance Tax is reduced because the estate includes assets that Inheritance Tax has recently been paid on
- ‘Benham’ grossing (https://www.gov.uk/hmrc-internal-manuals/inheritance-tax-manual/ihtm26172) — where the will has specific instructions about how the residue should be divided between chargeable and exempt beneficiaries
In these situations, we’ll do the grossing up for you. Request this in the additional information box or cover letter when you complete your Inheritance Tax account on form IHT400.

Before you start

You’ll need a copy of the will. You’ll also need to know these details about the estate:
- the total value of the assets and liabilities (https://www.gov.uk/valuing-estate-of-someone-who-died)
- the nil rate band that applies, which is the Inheritance Tax threshold (https://www.gov.uk/inheritance-tax) minus any lifetime gifts (https://www.gov.uk/guidance/work-out-inheritance-tax-due-on-gifts)
- if any transferable nil rate band (https://www.gov.uk/guidance/transferring-unused-basic-threshold-for-inheritance-tax) applies
- if any residence nil rate band (https://www.gov.uk/guidance/check-if-you-can-get-an-additional-inheritance-tax-threshold) applies
- if the reduced rate of Inheritance Tax (https://www.gov.uk/inheritance-tax-reduced-rate-calculator) applies
Use the calculator

To use the calculator, you’ll need to:

Get all of your information together before you start. You’ll use the calculator online and you cannot save your progress

Use the calculator

Print the results

Post them to HMRC along with your Inheritance Tax account (IHT400) (https://www.gov.uk/government/publications/inheritance-tax-inheritance-tax-account-iht400)

Start now (https://tax.service.gov.uk/guidance/IHT-grossing-up-calc)

Interaction rules

Interaction rules apply if the estate gets agricultural or business relief, and all of these apply:
- the will has at least one specific gift of property
- the will has property subject to tax relief that’s not given as a specific gift
- some of the estate is exempt from Inheritance Tax
You can use the calculator if interaction rules apply, but only after manually deducting agricultural or business relief.

Interaction calculations can get complicated. We’ll do them for you if you request it when you submit your return.

If something changes

If something changes after you submit your Inheritance Tax account, you can submit a corrective account (https://www.gov.uk/government/publications/inheritance-tax-corrective-account-c4) with new grossing up.

Use the calculator again, updating any figures that have changed. Print your results and post them with the corrective account.

Detailed guidance

For detailed information about grossing up, check the Inheritance Tax manual section on ‘Calculating the chargeable estate’ (https://www.gov.uk/hmrc-internal-manuals/inheritance-tax-manual/ihtm26000).