Seed Enterprise Investment Scheme (SEIS): Rules and Tax Reliefs Explained

The Seed Enterprise Investment Scheme (SEIS) targets the earliest stage of the venture funding lifecycle — companies that are often too young, too small, or too early-revenue for even standard EIS qualification. To compensate investors for the higher risk involved, SEIS offers the most generous tax reliefs available under any UK investment scheme. For UK taxpayers with appetite for early-stage investing, or for internationally mobile investors with UK tax exposure, SEIS deserves serious consideration as part of a broader tax and investment planning framework. This guide explains how SEIS works, who qualifies, and how to use it effectively, as of 2026.

SEIS at a Glance

SEIS was introduced in 2012 specifically to stimulate investment in the very earliest stage of a company's life. As of 2026, the scheme offers:

• Income tax relief at 50% of the amount invested, up to £200,000 per annum per investor
• Capital gains tax exemption on gains from SEIS shares sold after three years (provided income tax relief was given and not withdrawn)
• CGT reinvestment relief: 50% of a capital gain from another asset can be exempted if the proceeds are reinvested in SEIS shares (subject to annual investment limits)
• Loss relief: where SEIS shares are disposed of at a loss, the net loss (after income tax relief) can be set against income or capital gains
• Inheritance tax exemption after two years of ownership, through Business Property Relief

The income tax relief rate of 50% is the most generous of any UK tax relief on direct equity investment. On a £200,000 annual investment, the maximum income tax saving is £100,000 — subject to the investor having sufficient income tax liability to absorb it.

How SEIS Compares to EIS

SEIS and EIS are complementary, not competing. EIS targets somewhat more established companies; SEIS targets the seed stage specifically. A company can raise SEIS funding first, then graduate to EIS for later funding rounds. Investors can hold SEIS and EIS shares simultaneously in the same company, provided the correct sequencing is maintained.

The key differences are:

Feature	SEIS	EIS
Income tax relief	50%	30%
Annual investor limit	£200,000	£1m (£2m for KICs)
Company size limit	≤25 employees, ≤£350k gross assets	≤250 employees, ≤£15m gross assets
Company age	Within first three years of trading	First seven years (ten for KICs)
Maximum company raise	£250,000 lifetime	£12m (£20m for KICs)
CGT relief	50% reinvestment relief + exemption	Deferral + exemption

Investor Qualifying Conditions

To claim SEIS income tax relief, an investor must:

• Be a UK taxpayer with income tax against which to set the relief
• Not be "connected" to the company: broadly, not holding more than 30% of the ordinary share capital and not being an employee of the company at the time of investment (directors can qualify — the definition of "connected" is narrower for SEIS than might be assumed)
• Subscribe for new, fully paid ordinary shares
• Hold the shares for at least three years from the date of issue (or from the date trading commenced, if later)

The annual investment limit of £200,000 applies per investor per tax year. Unlike EIS, there is no carry-back mechanism for SEIS (relief can only be claimed in the year of investment). For investors with high income in a particular year — perhaps from a business sale or bonus — using the £200,000 SEIS allowance in that year can provide significant income tax reduction.

Company Qualifying Conditions

The company requirements for SEIS are stricter than EIS, reflecting the scheme's focus on very early-stage businesses:

• Size: must have no more than 25 full-time equivalent employees and gross assets not exceeding £350,000 immediately before the investment
• Age: the company must have been trading (or preparing to trade) for no more than three years at the date of investment
• Incorporation: must be UK-incorporated and tax-resident
• Unquoted: must not be listed on a recognised stock exchange (AIM qualifies)
• Lifetime raise limit: the company can raise a maximum of £250,000 under SEIS in total (across all investors and rounds)
• Qualifying trade: similar exclusions to EIS apply — financial services, property development, legal and accountancy, hospitality in some circumstances, and other specified activities are excluded
• New company rule: the company must not have received EIS or VCT investment before the SEIS investment (SEIS must come first)

HMRC advance assurance is available and strongly advisable before investing. Without assurance, the investor bears the risk that the company is later found not to have met qualifying conditions.

The CGT Reinvestment Relief: A Powerful Planning Tool

One distinctive feature of SEIS is the CGT reinvestment relief, which has no direct equivalent in EIS. Under this relief, 50% of a capital gain from the disposal of any asset (not just business assets) can be exempt from CGT if the proceeds are reinvested in qualifying SEIS shares within the same tax year.

Example: An investor sells quoted shares generating a £100,000 gain. They invest £50,000 in SEIS shares in the same tax year. They can exempt £25,000 of their gain (50% of the £50,000 invested) from CGT, saving £4,500 at the 18% CGT rate, or £6,000 at 24% depending on their position — in addition to the 50% income tax relief on the SEIS subscription itself (£25,000).

The relief applies to gains reinvested up to the SEIS annual limit (£200,000). For investors realising significant capital gains — particularly in a year of portfolio rebalancing or property disposal — this relief adds another layer of tax efficiency to an already generous scheme.

Risk and Return Profile of SEIS Investments

The generous tax reliefs compensate for the genuinely high risk of seed-stage investing. HMRC data and industry research consistently show that the majority of seed-stage companies fail to return capital to investors. Even a diversified portfolio of SEIS investments may not return investors' capital before tax relief.

Understanding the risk profile is essential:

Failure rate: seed-stage companies have a high mortality rate, particularly in the first three years — the same period during which SEIS relief must not be withdrawn. Failure during this period means income tax relief is not clawed back (the investment simply fails) but also means the loss relief calculation kicks in.

Loss relief calculation: If an investor pays £200,000, receives £100,000 income tax relief (50%), and the investment fails entirely, the net loss to the investor is £100,000. If that £100,000 is claimed as loss relief at a marginal income tax rate of 45%, the additional saving is £45,000 — so the actual out-of-pocket loss is £55,000 on a £200,000 investment. The effective downside is significantly cushioned by the tax system.

Upside: if the investment succeeds and the investor sells after three years, all gains are free of CGT. On a £200,000 investment that grows to £600,000 over five years, the £400,000 gain would be entirely tax-free — a considerable benefit for an investor who would otherwise pay CGT at 24%.

SEIS Funds and Platforms

Individual company selection in SEIS requires the ability to assess very early-stage businesses — a skill that most investors do not possess independently. SEIS funds pool investor capital across a portfolio of qualifying companies, offering diversification and professional management.

Points to evaluate when selecting a SEIS fund:

• Track record: can the manager demonstrate returns across previous funds, including both successes and failures?
• Deal flow quality: does the manager have access to high-quality deal flow from recognised ecosystems (university spinouts, accelerators, sectoral clusters)?
• Fees: SEIS fund charges typically include a management fee (1–2% of funds invested per annum) and a performance fee (20% of gains above a hurdle). These materially reduce net returns and should be understood in the context of expected gross returns.
• Investment focus: some SEIS managers focus on specific sectors (deep tech, life sciences, fintech). Sector specialisation can indicate genuine expertise or alternatively narrow the diversification.
• Tax reporting: ensure the fund provides SEIS 3 compliance certificates in a timely manner — investors cannot claim relief without them.

For Internationally Mobile Investors

As with EIS, the income tax relief element of SEIS requires UK income tax liability against which to set it. Non-UK residents with no UK income cannot access income tax relief. However:

• Returning to UK residence in the tax year of investment restores access to income tax relief, and any income earned from the date of return qualifies.
• CGT reinvestment relief is accessible to investors with UK capital gains — including gains on UK land and property, which remain taxable for non-residents.
• IHT benefits through BPR continue to apply to former UK-domiciled or long-term-UK-resident investors.

For investors planning a move back to the UK, or who maintain UK income-producing assets, SEIS deserves careful consideration in the year of return or in years of elevated UK income.

Compliance and Record-Keeping

SEIS compliance obligations fall on both the company and the investor:

Company: must issue SEIS 3 certificates (obtained from HMRC) to investors once qualifying trading conditions are met. Cannot issue certificates speculatively in advance of meeting conditions. Must not cease to qualify within three years of the investment.

Investor: must retain SEIS 3 certificates and submit claims via self-assessment. Cannot sell shares within three years. Must report any event that causes shares to cease to qualify (e.g. if the company is acquired within three years, income tax relief is withdrawn). Must retain records for at least five years after the relevant tax return filing deadline.

How Global Investments Can Help

Global Investments advises clients on the strategic integration of SEIS into a wider tax and investment planning framework. We help clients assess whether SEIS is appropriate given their UK tax residency position, income levels, and investment risk tolerance. We can introduce clients to reputable SEIS fund managers with demonstrable track records, and ensure that SEIS investments are considered alongside EIS, VCT, and other tax-efficient vehicles as part of a coherent annual planning process.

For business owners in a sale year, or individuals with elevated income from other sources, SEIS can provide meaningful tax reduction — but only as part of a structured plan that accounts for risk and the overall portfolio.

This guide is for general information only and does not constitute financial, tax, or investment advice. SEIS tax reliefs are subject to qualifying conditions and personal circumstances; reliefs may be withdrawn. SEIS investments are high-risk and capital can be lost entirely. All information reflects our understanding as of 2026; tax rules are subject to change. Always seek professional advice specific to your situation.