Claiming tax relief using a SEIS3 certificate

Katerina Galkina · EN · 07/10/2026

Check the certificate and share issue date

The company issues SEIS3 following the relevant HMRC approval process. An advance assurance letter, bank payment confirmation or platform offer is not a substitute. HMRC's guidance ↗ also stresses that company eligibility does not automatically establish investor eligibility.

Check your name, the company, Unique Investment Reference, subscription amount and share issue date. Match the issue date to the tax year, rather than relying solely on the date you transferred money. Ask the company to correct any certificate error, and retain the subscription agreement and payment evidence.

Calculate the relief actually available

Current rules provide Income Tax relief of up to 50% of a qualifying investment, with a £200,000 annual investment limit. However, relief is restricted by your UK Income Tax liability. If that liability is insufficient, SEIS does not become an unconditional payment of half the investment.

Check the investor conditions, including connections with the company, ownership interests, employment, linked loans and other relevant arrangements. Do not automatically apply EIS conditions to SEIS. For a complicated structure, use HMRC's SEIS procedure guidance ↗ and an adviser familiar with venture capital schemes.

Choose the claim year and procedure

The 2026 HS393 helpsheet ↗ explains reporting through Self Assessment and the details required for each investment. You cannot claim for an investment before receiving SEIS3. If the certificate arrives after your return, use the applicable separate claim or amendment procedure.

In certain circumstances, carry-back to the preceding year is available, subject to that year's limit and relief already claimed. Do not assume unused relief can be carried forward freely. Before submitting, make a schedule of certificates, share issue years, the year selected for relief and Income Tax liability; this helps prevent duplicate claims.

Keep evidence after receiving relief

Continuing compliance matters: selling shares or changing circumstances can reduce or withdraw relief. A three-year qualifying period does not guarantee liquidity or investment returns. Advance assurance is also not an HMRC recommendation to invest.

Income Tax relief, Capital Gains Tax reinvestment relief and the consequences of a disposal require separate calculations. Do not combine them into one undifferentiated claim. Keep the certificates, computation, submitted form and HMRC acknowledgement. If you discover an error or receive notice that the company has breached conditions, check your notification obligations promptly rather than waiting until a subsequent sale.