Why SEIS Can Make Sense
You’ve used your ISA allowance and maxed out your pension contributions, and now you’re looking at what else might help you invest for the future while saving some tax.
If you’ve read our articles on EIS and VCTs, there’s another scheme worth understanding: the Seed Enterprise Investment Scheme, or SEIS.
It supports businesses at the very beginning of their journey. The tax reliefs are generous because the risks are substantial.
⚠️ SEIS investments are risky and illiquid. You could lose everything you invest, and there may be no easy way to sell your shares. Tax relief reduces the financial impact in qualifying cases; it does not make the investment safe.
What SEIS actually is
SEIS encourages individuals to subscribe for new shares in qualifying start-ups. Your money goes into the business to help it develop and grow.
For investors, the attraction is a combination of income tax relief, potential capital gains tax savings and loss relief. For a young business, those incentives can help secure funding that might otherwise be difficult to come by.
The headline is 50% income tax relief
You can claim income tax relief at 50% on qualifying investments of up to £200,000 per tax year. That means a potential tax reduction of £100,000, provided you have enough UK income tax liability.
💡 A £20,000 investment could reduce your income tax bill by £10,000.
Note that this is a reduction in the tax you owe, rather than a deduction from your taxable income.
You cannot reclaim more income tax than your liability allows. You can elect to carry some or all of the investment back to the previous tax year, subject to that year’s limits and your available tax liability. Unused relief cannot simply be carried forward.
A separate saving on capital gains
SEIS reinvestment relief can exempt 50% of a qualifying gain reinvested into SEIS shares, up to £100,000 of exempt gains per tax year. You must also receive SEIS income tax relief on the relevant investment.
For example, reinvesting a £40,000 chargeable gain into qualifying SEIS shares could exempt £20,000 of that gain. That is £20,000 removed from the taxable gain, not £20,000 deducted from the tax bill.
✅ This is one of the clearest differences from EIS. EIS generally defers a qualifying gain. SEIS can permanently exempt part of it, provided the conditions remain satisfied.
Timing matters: the gain and the investment must align with the relevant tax year, including any valid carry-back election.
What happens if the investment fails
Loss relief is an important part of the calculation, although nobody should invest expecting to rely on it.
Suppose a higher-rate taxpayer invests £20,000, receives the full SEIS income tax relief, and the shares later become worthless. Assuming the original relief is retained and the remaining loss qualifies for relief entirely at 40%:
| Worked example | Amount |
|---|---|
| Original investment | £20,000 |
| Income tax relief at 50% | £10,000 |
| Remaining allowable loss | £10,000 |
| Further loss relief at 40% | £4,000 |
| Net loss after these tax reliefs | £6,000 |
⚠️ This simplified example excludes fees and any CGT reinvestment relief. Loss relief requires a valid disposal or negligible-value claim, and sufficient taxable income for the assumed saving. It is not an automatic payment when a company runs into trouble.
You would still have lost £6,000. The reliefs soften the impact, but a failed investment remains a loss.
What happens if the business succeeds
If you sell your SEIS shares at a profit after holding them for at least three years, the gain can be exempt from CGT, provided the income tax relief and other qualifying conditions are satisfied.
SEIS dividends do not enjoy the special tax exemption available to VCT dividends.
Qualifying shares may also attract inheritance tax Business Relief after two years. This has separate conditions, and SEIS status alone is insufficient. From 6 April 2026, the standard individual allowance for 100% relief is £2.5 million across qualifying agricultural and business property, with 50% relief above it. Other business interests can use that allowance too.
The company has to qualify too
SEIS is designed for genuinely young businesses. Broadly:
✔️ The qualifying trade must be no more than three years old
✔️ Gross assets must not exceed £350,000 before investment
✔️ The company and its subsidiaries must have fewer than 25 full-time equivalent employees
A company can raise up to £250,000 under SEIS in total, with certain other aid counting towards that limit. It cannot receive SEIS investment after EIS or VCT funding, so the order of fundraising matters. The trade, the shares and the use of funds must also meet detailed conditions.
The pitfalls worth taking seriously
⚠️ Your money may be tied up for years. The three-year holding period is a tax condition, not a promise that someone will buy your shares at the end of it.
⚠️ Your relationship with the company matters. Broadly, you and your associates must not hold more than 30% of its shares or voting rights, and there are further substantial-interest tests. Being a director does not itself disqualify you under SEIS, but the other investor conditions still apply. Don’t assume investing in your own or a family member’s company qualifies.
⚠️ The reliefs can be withdrawn. Selling too early, receiving certain benefits from the company, or breaching qualifying conditions can put the tax savings at risk.
⚠️ The paperwork matters. You need an SEIS3 certificate before claiming. HMRC advance assurance is neither an endorsement of the investment nor a guarantee that you personally qualify for relief.
⚠️ The investment still needs to stand up to scrutiny. Look at the business, the management, the valuation, the fees and the prospects. A generous tax incentive cannot rescue a weak commercial proposition.
Where SEIS may fit
SEIS may have a place where three things are true at once: you have a tax liability that makes the reliefs useful, you have surplus money you can genuinely afford to lose, and you’re willing to back very young businesses for the long term.
💡 Using your pension or ISA allowances does not automatically make SEIS the next suitable step. Your cash needs, your existing investments and your exposure to your own business all matter.
At Blueski Financial Synergy, we can help you understand your tax position, assess the available reliefs and plan the timing alongside your wider business and personal goals. A suitably authorised financial adviser can help assess investment suitability and specific opportunities.
Want to understand whether SEIS could have a place in your tax planning? Book a meeting with Blueski and let’s look at the numbers before you commit.
General information based on the rules as checked on 23 September 2026. This article is not personal investment, tax or legal advice. Reliefs depend on individual circumstances and continued compliance, and tax rules can change. SEIS investments are high risk and illiquid.
Sources and further reading
HMRC — SEIS income tax relief and carry-back
HMRC — Tax relief for investors using venture capital schemes
HMRC — SEIS helpsheet HS393 for 2026
HMRC — Share loss relief helpsheet HS286 for 2026
GOV.UK — Business Relief for Inheritance Tax
HMRC — SEIS company conditions
HMRC — SEIS investor conditions
#SEIS #SeedEnterpriseInvestmentScheme #TaxPlanning #Startups #CapitalGainsTax #VFD #CFO
