SEIS

TL;DR

UK tax-advantaged scheme giving angels up to 50% income-tax relief on up to £200k/yr invested into very early-stage UK companies.

The Seed Enterprise Investment Scheme (SEIS) is HMRC's flagship incentive for very-early-stage UK startups. Qualifying companies — under three years old, fewer than 25 employees, and under £350,000 in gross assets — can raise up to £250,000 of SEIS investment in their lifetime. Individual investors get 50% income-tax relief on the amount invested, capital-gains exemption on a future exit if held for three years, and loss relief if the investment fails.

In practice, founders apply for Advance Assurance from HMRC before raising, then issue SEIS-eligible shares (ordinary, not preference) and file SEIS1/SEIS3 forms so investors can claim relief. The scheme is so attractive that most UK angel cheques expect SEIS treatment as the default — companies that fail to qualify often see cheque sizes drop sharply.

Formula

Investor Relief = min(Investment, £200,000) × 50%

• Investment — Amount the individual subscribes for SEIS-eligible shares in the tax year (UK only)
• £200,000 — Annual SEIS subscription cap per investor as of tax year 2024/25

Capital-gains exemption on the eventual exit is separate from the 50% income-tax relief and requires the shares to be held for at least three years.

Worked example

A London angel writes a £40,000 SEIS cheque into a fintech. They claim £20,000 back via income-tax relief (40k × 50%), pay £0 capital-gains tax on any exit if held 3+ years, and claim loss relief at their marginal rate if the company fails — capping their downside at roughly £14,000 against a 20–40× upside.

Common pitfalls

• Issuing preference shares or share classes with rights that disqualify the round.
• Burning the SEIS allowance early and locking yourself out of the bigger EIS pool.
• Spending raised funds before issuing shares — relief only attaches to shares paid up in cash.

When this shows up in a pitch deck

UK seed decks usually call out 'SEIS Advance Assurance secured' on the Use of Funds slide so angels know their cheques will qualify.

Related terms

• EIS — UK scheme offering investors 30% income-tax relief on up to £1m/yr (£2m if knowledge-intensive) in qualifying UK growth-stage companies.
• Advance Assurance — Non-binding HMRC pre-clearance that a UK company's planned share issue likely qualifies for SEIS or EIS, used to de-risk angel investment.
• ASA (Advance Subscription Agreement) — UK SEIS/EIS-compatible alternative to a SAFE: cash paid up-front for shares issued at the next round, with a 6-month longstop to keep relief.
• SAFE — Y Combinator's Simple Agreement for Future Equity — a contract that gives an investor the right to equity in a future priced round, with no debt or interest.
• Pre-Seed — The earliest priced or convertible round, typically raised on an idea, prototype, or very early traction with $250K–$2M from angels and pre-seed funds.

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