Calculate IHT with Business Relief (100%/50%) under current rules AND the April 2026 reform (£1m allowance, AIM at 50%) — see the extra tax coming.
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Compares Inheritance Tax on business assets under both regimes: today's Business Relief (100% on unquoted businesses and AIM shares, 50% on controlling quoted stakes and business land) versus the announced April 2026 reform — 100% relief capped at a £1,000,000 allowance then 50%, with AIM shares at a flat 50% — quantifying the additional IHT and the planning window.
£3m unquoted business plus £500,000 of other assets: £70,000 of IHT today, but £470,000 from April 2026 (£1m at 100%, £2m at 50%) — £400,000 of additional tax.
Enter the value of assets currently qualifying at 100% (unquoted business, shares).
Enter AIM shares separately — they lose the £1m allowance in 2026.
Add 50%-category assets, the rest of the estate and the nil rate band.
Compare the IHT under both regimes and the extra charge from April 2026.
Last data update
July 5, 2026
Sources and references
GOV.UK — Business Relief for IHT (gov.uk/business-relief-inheritance-tax); APR/BPR reform policy paper (Autumn Budget 2024).
The data in this calculator is updated regularly to reflect the latest official rates. When in doubt, consult the official sources listed above.
A business or interest in a business, and unquoted shares — including AIM-listed shares — owned for at least 2 years at death.
100% relief is capped at a £1,000,000 combined allowance (with Agricultural Relief); the excess gets 50% relief — an effective 20% IHT rate. AIM shares get 50% with no allowance.
Yes — IHT on qualifying business assets can be paid in 10 equal annual instalments, interest-free under the reform proposals.