AIM ISA / Business Relief ISA Portfolio
An ISA invested in qualifying AIM-listed shares that can benefit from Business Relief for IHT purposes. Combines the ISA tax shelter with 50% Business Relief on qualifying AIM shares held for 2 years (deaths from 6 April 2026).
By Omair SaoLast reviewed — rates for the 2026/27 tax year. See how we check our figures.
How It Works
You invest in AIM-listed shares within a Stocks & Shares ISA. A specialist provider selects qualifying shares meeting Business Relief criteria. After 2 years, qualifying shares attract 50% IHT relief. All income and gains remain ISA tax-free. You retain full access.
Tax Treatment
As an ISA, all income and gains are tax-free. Qualifying AIM shares held for 2 or more years attract 50% Business Relief for deaths on or after 6 April 2026, halving the IHT due on them.
Tax Advantages
- ISA tax shelter — all dividends and gains are tax-free
- 50% Business Relief on qualifying AIM shares after 2 years (100% applied to deaths before 6 April 2026)
- No need to give away assets or set up trusts
- Retain full control and access
Who Is This Suitable For?
Investors concerned about IHT who want to shelter wealth while maintaining access. Unlike trusts, AIM ISA portfolios remain fully accessible.
Worked Example: £100,000 AIM ISA held at death under the post-April 2026 rules
- 1Over five tax years you move £20,000 a year into an AIM portfolio ISA — £100,000 in total, ignoring growth — with dividends and gains ISA tax-free throughout.
- 2You die having held the qualifying AIM shares for more than two years.
- 3For deaths on or after 6 April 2026, shares on markets such as AIM get 50% Business Relief, so £50,000 of the £100,000 is left out of your IHT calculation.
- 4At the standard 40% IHT rate that is £20,000 less tax than a mainstream ISA of the same value, assuming your estate exceeds the nil-rate band.
Result: The IHT saving is now half what it was before April 2026, and it depends on the shares still qualifying on the day you die.
Illustrative figures using the 2026/27 rules on this page, last checked on 25 September 2026.
Advantages and Drawbacks
Advantages
- You keep full ownership and access, unlike a gift or a trust, and can sell if circumstances change.
- The two-year qualifying period is short compared with the seven years a gift needs to leave your estate.
- Existing ISA money can be transferred in, so decades of ISA savings can be repositioned without losing the wrapper.
Drawbacks
- AIM shares are volatile and thinly traded; a bad year can wipe out many years of expected IHT saving.
- Relief on AIM shares is limited to 50% for deaths from 6 April 2026, not the 100% quoted in older guides.
- Qualification is judged company by company on the date of death; a takeover, main-market listing or change of activity can remove relief without warning.
- Specialist AIM portfolio services charge more than a tracker fund, and the fees continue whether or not you ever benefit.
Notes for Limited Company Owners
If you still own a trading company, its shares may already qualify for 100% Business Relief within the £2.5 million allowance, so an AIM ISA may be adding relief you do not need. The AIM route becomes more relevant after a business sale, when cash proceeds sit fully inside your estate; AIM holdings fall in the 50% category, outside that allowance.
Common Mistakes
- Switching an elderly relative's whole ISA into AIM shares without considering whether they can cope with the volatility.
- Assuming every AIM company qualifies — property, finance and investment businesses generally do not.
- Forgetting that replacement shares start their own two-year clock unless the replacement property rules apply.
Who Should Avoid It
Anyone whose estate will fall below the nil-rate band, for whom the relief is worthless and only the risk remains, and those who cannot tolerate sharp falls in value.
Official Sources
The rules on this page come from the following official pages and were checked on 25 September 2026. Read how we check our figures.
Related Calculators
Frequently Asked Questions
Is Business Relief guaranteed?
No. It is assessed by HMRC on death and depends on whether shares qualify at that time. Not all AIM shares qualify.
What if I sell and reinvest?
The 2-year clock restarts for new shares. Proceeds remain within the ISA with no tax consequences.
AIM ISA vs trust?
AIM ISA is simpler — you retain control, no setup costs, no IHT entry charges. Trusts offer more certainty as assets are legally transferred.