Investor guides
SEIS explained for investors
The Seed Enterprise Investment Scheme, covered guide by guide: what it gives you, what it asks of you, and how to claim it.
SEIS is a UK government scheme that lets individual investors claim 50% income tax relief on up to £200,000 of investment a tax year into very early-stage companies, with capital gains and loss reliefs on top. It exists because the seed stage is where private capital is scarcest.
The reliefs do not change the underlying risk. They change what a loss costs and what a gain is worth, which is why SEIS is used to build a spread of small positions rather than a single large one.
The reliefs at a glance
- Income tax relief
- 50% of the amount invested, on up to £200,000 a tax year.
- Carry back
- Treat an investment as if made in the previous tax year.
- Capital gains exemption
- No CGT on a gain if the shares are held three years.
- Reinvestment relief
- Half of a gain reinvested into SEIS shares is exempt.
- Loss relief
- The loss after income tax relief set against income or gains.
The basics
What the scheme is, how it differs from EIS, and whether you qualify to use it.
What is SEIS? A plain-English guide for investors
What SEIS is, which reliefs it carries, who it is designed for, and the conditions attached to every one of them.
Read the guideSEIS vs EIS: which scheme applies, and when
A side-by-side comparison of the two venture capital schemes, and how a single funding round can use both in sequence.
Read the guideWho can invest under SEIS: eligibility and the connection rules
The investor-side conditions: UK tax liability, the 30% interest test, the employee rule, and what counts as being connected to the company.
Read the guideThe reliefs
Each of the four reliefs, what triggers it and how it is calculated.
SEIS income tax relief: how the 50% works in practice
How the 50% relief is calculated, what caps it, and what happens when your tax liability is smaller than your entitlement.
Read the guideSEIS loss relief: what happens when a company fails
How the net loss is calculated, the choice between setting it against income or gains, and what it means for the real downside on an SEIS position.
Read the guideSEIS capital gains: exemption and reinvestment relief
Disposal relief and reinvestment relief explained, including the conditions on each and how they interact with income tax relief.
Read the guideSEIS carry back: claiming against last year's tax
What carry back does, when it is worth using, the limits that still apply, and how to elect for it.
Read the guideThe rules
The thresholds and conditions that decide whether relief is given and kept.
SEIS limits: company caps, investor limits and the allowance
Every SEIS threshold in one table, what each one is measured against, and what happens when a company outgrows them.
Read the guideThe SEIS three-year holding period and how relief is withdrawn
The qualifying period, the events that trigger withdrawal or reduction of relief, and who has to tell HMRC.
Read the guideAdvance assurance and the SEIS3 certificate
What advance assurance is worth, how the compliance process works, and when you can expect the SEIS3 that lets you claim.
Read the guidePutting it to work
Making the claim, and building a portfolio rather than a single position.
How to claim SEIS relief on your tax return, step by step
What you need before you start, where each figure goes, the deadlines that apply, and what to keep on file.
Read the guideBuilding an SEIS portfolio: spread, pacing and position size
A practical framework for constructing an SEIS portfolio: how many holdings, how large, over how long, and what to keep in reserve.
Read the guideImportant
These guides are general information, not investment, tax or legal advice. Investing in early-stage companies puts your capital at risk, the shares are illiquid, and tax reliefs depend on your own circumstances and on the company keeping its qualifying status. Take independent advice before you invest.
Related reading
Investing in venture-built companies
SEIS is the tax framework. The companies themselves are the decision.