Shares traded on the Alternative Investment Market can still cut your inheritance tax bill, but the AIM inheritance tax relief available since 6 April 2026 is half what it used to be. Qualifying AIM holdings now receive 50% Business Relief rather than 100%, which reduces the effective inheritance tax rate on those shares from 40% to 20%.1GOV.UK. Changes to Agricultural Property Relief and Business Property Relief That is still a meaningful saving, and AIM shares remain one of the few investments that reduce inheritance tax while letting you keep full control of your money during your lifetime.
Why AIM Shares Get Business Relief at All
Business Relief reduces the taxable value of qualifying business assets when someone dies. AIM shares qualify because of a quirk in how the law defines “quoted.” A share is quoted only if it sits on a recognised stock exchange’s official list. AIM is operated by the London Stock Exchange, but its shares are admitted to trading rather than officially listed, so the legislation treats them as unquoted.2UK Parliament. Inheritance Tax Act 1984 Section 105 That places them in the same relief category as shares in a private trading company.
Before April 2026, that meant 100% relief and no inheritance tax on qualifying AIM holdings. Since 6 April 2026, the rate is 50%: half the value of the shares drops out of the inheritance tax calculation and the other half is taxed at the usual 40%.1GOV.UK. Changes to Agricultural Property Relief and Business Property Relief A separate £2.5 million allowance for assets that still receive 100% relief covers private business interests and agricultural property, but AIM shares are explicitly excluded from it. There is no tranche of an AIM portfolio that still qualifies for full relief.3UK Parliament. Chapter 7: Background to Agricultural and Business Property Reliefs
The Two-Year Holding Rule
You cannot buy AIM shares on a Thursday and get the tax break on Friday. Business Relief only applies if the deceased owned the qualifying shares for at least two continuous years before death.4GOV.UK. Business Relief for Inheritance Tax – What Qualifies for Business Relief Die inside that window and the shares sit in the estate at full value with no relief. That is a real risk: you carry market exposure for at least two years before any tax benefit crystallises, and the timing of death is not something you control.
The replacement property rules give you room to trade. If you sell one qualifying AIM holding and buy another, the clock does not necessarily restart. You can combine your ownership periods across the old and new shares, provided the combined period adds up to at least two years within the five years before the transfer of value.5UK Parliament. Inheritance Tax Act 1984 Section 107 Relief on the replacement shares is capped at what you would have received on the original, so swaps cannot be used to inflate the relievable amount. In practice you can actively manage an AIM portfolio without losing the qualifying period, provided any gaps between selling and buying are short.
Which AIM Companies Actually Qualify
Not every AIM company qualifies. The shares must be in a company whose business is mainly trading rather than mainly investing. Companies that primarily deal in land, buildings, or securities, or that hold investments, are excluded.4GOV.UK. Business Relief for Inheritance Tax – What Qualifies for Business Relief That rules out real estate investment vehicles, investment holding companies, and most financial trading businesses.
HMRC’s test is less mechanical than it might sound. There is no single bright-line percentage. HMRC looks at the business “in the round,” weighing the value of assets used in trading versus investment, the time directors and staff spend on each, how turnover and profits split between the two, and how the company describes itself in its own accounts.6HM Revenue & Customs. Shares and Assets Valuation Manual – SVM111150 – IHT Business Property Relief: Wholly or Mainly A company with significant investment income can still pass if its core operations involve genuine trading, but the assessment is a judgment call on the facts of each case.
A company that qualifies today might not qualify in three years if its business model shifts. Anyone holding AIM shares for inheritance tax reasons needs to keep an eye on what those companies actually do. A business that pivots from manufacturing into property development, or starts accumulating a large investment portfolio, can quietly lose its qualifying status without any announcement.
What the Saving Looks Like
Inheritance tax applies at 40% to the portion of an estate above the £325,000 nil-rate band, or £500,000 where the residence nil-rate band also applies.7GOV.UK. Inheritance Tax Nil-Rate Band and Residence Nil-Rate Band Thresholds From 6 April 2026 to 5 April 2028 Take an estate of £1,000,000 including £400,000 of qualifying AIM shares, with only the basic nil-rate band available. Without Business Relief, £675,000 is taxable and the bill is £270,000. With 50% relief on the AIM shares, £200,000 drops out of the estate, leaving £475,000 taxable and a bill of £190,000. An £80,000 saving is real money, even though the old regime would have saved £160,000.
AIM Shares Inside an ISA
Since 2013, AIM shares have been eligible for stocks and shares ISAs, and the wrapper stacks with Business Relief. During your lifetime, dividends are free from income tax and any growth is free from capital gains tax.4GOV.UK. Business Relief for Inheritance Tax – What Qualifies for Business Relief On death, the qualifying shares still attract 50% Business Relief, just as they would outside an ISA. The wrapper does not interfere with the relief and the relief does not interfere with the wrapper.
The combination is less powerful than it was before April 2026, when the ISA sheltered income and gains during life and Business Relief wiped out the entire value at death. Now half the value still faces inheritance tax. Even so, the pairing remains one of the more efficient structures available: no income tax and no capital gains tax while alive, and a 20% effective inheritance tax rate rather than 40% at death.
The Investment Risks
The tax numbers look attractive on a spreadsheet, but AIM shares carry investment risks that can easily swallow the saving. These are smaller companies, often earlier in their growth cycle, with share prices that can move sharply. Most AIM stocks trade infrequently, with wider bid-ask spreads and higher price volatility than main market shares, and getting out quickly at a fair price can be genuinely difficult.
A few risks deserve particular attention:
- Low trading volumes mean you may not be able to sell at the price on screen, especially in larger quantities. The gap between what buyers will pay and sellers will accept is often much wider than on the main market.
- Smaller companies fail at higher rates. An AIM share that becomes worthless saves nothing on inheritance tax and costs the entire investment.
- A company may stop meeting the trading test, stripping the relief from your shares without warning. You bear the investment risk and get no tax benefit.
- Investors tempted to load up on AIM shares for the tax break can end up dangerously concentrated in a volatile, illiquid corner of the market.
At 100% relief, the trade was straightforward: accept higher investment risk in exchange for zero inheritance tax. At 50% relief, the tax saving is still real, but it needs to be weighed against the very real possibility that an AIM portfolio falls in value by more than the tax saved.
Keeping Ownership Versus Making Gifts
One of the main attractions of AIM shares is that you keep your money. With outright gifts, you lose access to the capital, and the gift only becomes fully exempt from inheritance tax if you survive seven years. Die within three years and the gift is taxed at the full 40% rate. Die between three and seven years and taper relief applies on a sliding scale, starting at 32% and dropping to 8%.8GOV.UK. How Inheritance Tax Works: Thresholds, Rules and Allowances
AIM shares stay yours. You can sell them, spend the proceeds, reinvest, or hold. The qualifying period is two years rather than seven, and once qualified the relief applies automatically at death. Nothing has to be given away and no control is lost over how the money is used. Trusts offer another route but come with formal legal structures, ongoing administration, and potential tax charges at ten-year intervals. AIM shares sit in a brokerage account and need no special legal arrangements. The trade-off is that you accept investment risk and a lower level of relief than a completed seven-year gift would eventually provide.
Claiming the Relief at Probate
Qualifying AIM shares are still part of the estate and must be reported. The executor claims Business Relief when completing the inheritance tax account by filling in both form IHT400 and schedule IHT413, which specifically covers business and partnership interests.9GOV.UK. Inheritance Tax – Business and Partnership Interests and Assets IHT413 HMRC then reviews whether the shares actually qualify, including whether the company met the trading test and whether the two-year holding period was satisfied.10GOV.UK. Business Relief for Inheritance Tax
Getting this wrong is expensive. If the executor claims relief on shares that turn out not to qualify, HMRC will assess additional tax plus interest. Keeping records of purchase dates, holding periods, and the trading activities of the companies during your lifetime makes the executor’s job much easier and reduces the risk of a disputed claim.