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by Undo Capital
December 15, 2025
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What Is the SEIS1 Form?

The SEIS1 form is the compliance statement a company submits to HMRC to confirm it meets all SEIS rules before investors can claim tax relief.

SEIS1 Form Meaning

The SEIS1 form's meaning centres on securing HMRC approval for investor tax benefits. To define SEIS1 form in practice, a company can submit it only after it has spent the SEIS funds on a qualifying trade and has been trading for at least four months. HMRC reviews the submission, and once approved, issues SEIS3 certificates that investors use to claim their tax relief. A clear SEIS1 form definition is essential because incorrect or incomplete submissions can delay or jeopardise SEIS eligibility. The SEIS1 stands for the key compliance step that unlocks SEIS advantages for investors.

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Disclosure Notice: This communication is issued by Undo Capital Limited (“Undo Capital”) and is provided strictly for informational purposes only. It contains general information and should not be relied upon as accounting, business, financial, investment, legal, tax, or other professional advice. Undo Capital is not regulated by the Financial Conduct Authority (FCA) and does not provide investment, financial, or tax advice. Our services are designed to assist startups and businesses with company formation, legal agreements, and funding-related documentation. Nothing in this communication constitutes, or should be construed as, a recommendation, offer, or solicitation to purchase or sell any security or financial instrument.
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Undo Capital handles everything — SEIS/EIS, investor agreements, share issue, and filings — in one simple, automated platform.

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Disclaimer: Our services are designed to assist startups and businesses with company formation, legal agreements, and funding-related documentation. We do not provide investment advice, financial advice, or tax advice, nor are we regulated by the Financial Conduct Authority (FCA). Participating in startups and early-stage enterprises carries inherent risks, including limited liquidity, absence of dividends, potential loss of investment, and dilution. Any decisions regarding investments should be made independently by the investor as part of a well-diversified portfolio.