IHT After the BPR Cap: What the £2.5m Limit Means

You have spent fifteen or twenty years building a business. It is worth £3.5m. Maybe £5m, maybe £6m. The plan was always that it would pass on intact. The plan was always that the next generation would not have to write a cheque to HMRC on the day the will is read. That plan may now be wrong, by an amount that is not a rounding error. The £2.5m BPR and APR cap effective from 6 April 2026 is the reason. The mechanics are not in the headline number, but they are also not in the small print. They are in the part most people skip.

This page is the deeper read. It works through the exact rule, the spousal transferability mechanic, the AIM and unlisted carve-out, and three worked examples across a trading business, a working family farm, and a mixed estate. It closes with five things not to do this month, then one specific action. It is the companion to the business property relief 2026 changes overview. Read them in either order.

1. The exact rule, in plain English

Two reliefs do the heavy lifting when a trading business or working farm passes on: Business Property Relief (BPR) for shares in an unlisted trading company, sole trade or partnership interests, and certain business property, and Agricultural Property Relief (APR) for the agricultural value of qualifying land and some farm buildings. Before 6 April 2026, both reliefs were 100 percent on the whole of the qualifying value. From that date, both reliefs are 100 percent only on the first £2.5m of combined qualifying business and agricultural property per individual. Above £2.5m, the relief rate drops to 50 percent. Source: Finance Act 2024 amendments to the Inheritance Tax Act 1984, GOV.UK.

The £2.5m is a combined allowance. It is not £2.5m of BPR plus £2.5m of APR. A farmer with £3m of agricultural value and no business assets has used £500,000 of the £2.5m over the threshold. A business owner who also owns the farmland the business sits on is using one allowance across both asset classes. Source: HMRC Inheritance Tax Manual.

Where the £2.5m sits in the IHT stack is best read as a table. For a single person, the £0-IHT slice is built from four layers. The £325,000 nil-rate band (NRB) covers the first £325k of any estate. The £175,000 residence nil-rate band (RNRB) covers up to £175k of the family home if it passes to direct descendants. The £2.5m BPR/APR combined allowance covers the next slice of qualifying business and agricultural property. The spouse or civil partner exemption covers anything that passes to the surviving partner. For a married couple on second death, the picture doubles, because unused allowances transfer.

2. Spousal transferability mechanics

The headline rule says "the unused £2.5m can pass between spouses." The reality is more specific, and the specifics matter. On first death, the will of the deceased usually directs the entire estate (or a defined slice of it) to the surviving spouse. Because of the spouse exemption, no Inheritance Tax is charged on that first transfer. The unused portions of the NRB, the RNRB (where it applies), and the £2.5m BPR/APR allowance are not "used" at all on first death. They sit with the deceased. The deceased's personal representative can elect to transfer them forward to the surviving spouse's estate. Source: HMRC Inheritance Tax Manual.

The election is what makes the second-death number small. Without it, the surviving spouse has their personal allowance only (NRB £325k plus RNRB up to £175k plus the £2.5m BPR/APR combined). With it, the surviving spouse has their own allowance plus the unused slice from the deceased. For a couple where each owns £3m of qualifying business property, the first death leaves the surviving spouse with a £2.5m slice from the deceased, plus their own £2.5m slice, plus their own NRB and RNRB. The combined £0-IHT headroom is therefore £5m of business property plus £500k of cash, against a £6m estate, leaving £500k that falls outside reliefs entirely. That £500k then runs through the standard 40 percent rate, producing an indicative £200,000 of Inheritance Tax.

What this means for the will is concrete. If the first will directs the business interest into a trust for the children rather than to the surviving spouse, the spouse exemption is bypassed. The £2.5m allowance on first death is then "used" against the trust, the transfer to the surviving spouse is reduced to the NRB and RNRB only, and the surviving spouse's estate on second death has lost the transferred BPR/APR slice. The will, the trust documents, and the share ownership need to be aligned with the family's intended outcome. A will drafted in 2014 against the pre-2026 BPR landscape is not necessarily the right will for 2026 and beyond. Source: HMRC Inheritance Tax Manual.

3. The AIM and unlisted carve-out

Qualifying shares designated as not listed on a recognised stock exchange, including AIM shares, receive 50 percent Business Property Relief in all circumstances. They do not share in the £2.5m 100 percent allowance. Source: Finance Act 2024, GOV.UK. The headline difference matters because two £1m shareholdings, one in an AIM-listed trading company and one in a main-market-listed trading company, are taxed in two completely different ways at death.

Imagine the holding in each. £1m of AIM shares in a qualifying trading company. After 50 percent relief, £500k of value is exposed to Inheritance Tax. Less the £325k NRB, £175k is taxable at 40 percent. That is £70,000 of indicative IHT. Now imagine the same £1m held in main-market shares. A main-market trading company share does not in itself qualify for BPR. The full £1m is exposed. Less the NRB, £675k is taxable at 40 percent. That is £270,000 of indicative IHT. The difference between the two structures is £200,000 of Inheritance Tax on identically-valued holdings. For a £2m AIM holding after 50 percent relief, £1m is exposed. Less NRB, £675k taxable, £270,000 of IHT. That is the outcome that surprises most people: a £2m AIM holding produces the same IHT as a £1m main-market holding.

There are two follow-on points most readers miss. First, AIM shares only get the 50 percent relief if the company is a "qualifying" company for BPR purposes. The company has to pass the same trading tests as an unlisted trading company. An AIM-listed investment company or AIM-listed shell does not qualify. Source: HMRC Inheritance Tax Manual. Second, the 50 percent rate has been the rule for AIM for many years. What changed on 6 April 2026 is the rest of the landscape. The relief itself is unchanged. The new framing is to compare AIM (50 percent, no £2.5m slice) to the new regime for unlisted shares (100 percent on £2.5m, then 50 percent). On that comparison, AIM has lost relative attractiveness above a certain size.

4. Three worked examples

The worked examples below use assumptions stated up front. They are illustrative, not forecasts. They are not advice. Real outcomes depend on ownership, valuation, debts, lifetime gifts, and the wider family situation. The numbers are here to show how the rule maps to the three most common situations.

5. Five things not to do this month

Most IHT mistakes are made in the six weeks before a Budget. Rumour arrives, advisers start fielding calls, clients transfer cash or shares to lock in reliefs that may already be locked in. The five rules below are the ones that get broken most often, in the specific context of the £2.5m BPR/APR cap.

6. The one specific monthly action

For a first-pass estimate of the IHT exposure on the rest of the estate, the inheritance planning check is a starting point. It does not model BPR or APR eligibility, which is fact-specific, but it will show the headline number. For the wider picture of whether the household finances are on track, see am I on track financially UK. For a worked example of what the Budget could do to a retirement number built on assumptions that pre-date the rule, see how the Budget affects your FIRE number.