SEIS Eligibility UK — Criteria, Rules & How to Qualify
A founder-grade briefing on SEIS eligibility, the criteria HMRC applies, the mistakes that lead to rejection, and why qualifying on paper is only the starting point for a credible Advance Assurance application.
What is SEIS eligibility?
SEIS eligibility refers to whether a UK company — and its proposed share issue — meets the statutory conditions of the Seed Enterprise Investment Scheme. Eligibility is the gating test HMRC applies before considering the wider commercial and risk-to-capital merits of an SEIS Advance Assurance request.
For founders preparing a fundraise, understanding SEIS criteria early prevents wasted legal cost, avoids rejection letters, and keeps investor timelines intact.
Who qualifies for SEIS in the UK?
SEIS is designed for very early-stage UK companies raising their first external equity capital. Broadly, a company qualifies where it is a UK-resident trading company, independently owned, carrying on (or preparing to carry on) a new qualifying trade, and genuinely exposed to investor capital risk.
Investors, in turn, must be UK taxpayers acquiring newly issued ordinary shares, holding them for at least three years, and not connected to the company as employees or substantial shareholders beyond the permitted thresholds.
Key SEIS eligibility criteria
The core statutory tests every UK startup must satisfy before HMRC will consider Advance Assurance.
- UK-incorporated, with a permanent establishment in the UK
- Less than 3 years of trading at the date of share issue
- Fewer than 25 full-time-equivalent employees
- Gross assets of £350,000 or less immediately before the share issue
- Carrying on a new qualifying trade (most trades qualify; some are excluded)
- Not controlled by another company; no qualifying subsidiaries that breach rules
- Maximum SEIS raise of £250,000 (lifetime SEIS cap)
- Funds used for a qualifying business activity within 3 years
- Shares must be new, fully paid ordinary shares with no preferential rights
- Genuine risk to the investor's capital (the risk-to-capital condition)
Common mistakes that lead to rejection
Most SEIS rejections are not caused by ineligible companies — they are caused by avoidable structural and narrative errors in the application. The recurring patterns we see include:
- Applying after trading has commenced more than 3 years ago, or after a non-qualifying trade has begun.
- Issuing shares with preferential rights, redemption features, or hidden anti-dilution mechanics.
- Group structures or parent-company arrangements that breach the independence requirement.
- Use-of-funds wording that signals working capital cover rather than growth and development.
- A weak or templated risk-to-capital narrative that HMRC reads as capital-preservation, not genuine risk.
- Missing or inconsistent documentation across pitch deck, articles, shareholder agreements and SH01 filings.
- Connected-party investors (directors, employees, >30% holders) listed without flagging the connection.
Why eligibility alone is not enough for Advance Assurance
Meeting the SEIS criteria is necessary but not sufficient. HMRC's Advance Assurance process applies a second, judgement-based layer: the risk-to-capital condition. This requires HMRC to be satisfied that the company is seeking to grow and develop its trade over the long term, and that the investment carries a genuine risk of capital loss.
A technically eligible company can still be refused Advance Assurance if its plan reads as low-risk, asset-backed, tax-motivated, or structured to protect investor capital. The quality of the narrative, the alignment of the cap table, and the coherence of the use-of-funds case are decisive — and this is where most founder-led applications under-perform.
Advanced Cases: Deep Tech, Biotech and Grant-Funded Startups
When SEIS eligibility intersects with scientific IP, public funding and complex equity, Advance Assurance becomes a structuring exercise — not a form-filling one.
SEIS eligibility becomes materially more complex for companies with:
- Scientific IP and R&D-heavy operating models, where revenue is years away and value sits in patents, know-how or licences.
- Grant funding already received (Innovate UK, Horizon Europe, ATF, BBSRC and similar) that must be reconciled against the use-of-funds and risk-to-capital case.
- Advisory board equity arrangements, options pools and consultant share grants that can distort the connected-persons and independence tests.
- Complex cap tables involving technical co-founders, university spin-out arrangements, founder loans, or convertible instruments left over from pre-seed activity.
In these cases, eligibility is not a checkbox — it is a careful structuring exercise. HMRC needs to see a coherent picture: that the grant-funded technical de-risking does not eliminate investor capital risk, that IP ownership sits cleanly inside the SEIS company, and that share classes and connected parties are documented in a way that reinforces rather than undermines the risk-to-capital narrative.
The CFO Stack prepares these applications regularly. Our work is built around clarity, defensibility and direct alignment with HMRC's current evaluative framework — so deep tech, biotech and grant-funded founders go into Advance Assurance with a submission that reads the way HMRC expects to read it.
If this sounds like you
A specific kind of founder benefits most from CFO-grade SEIS structuring — science-led, IP-heavy, and racing against an investor timeline.
I'm a founder/CEO of a deep tech company — in biotech, foodtech, agritech, robotics, advanced materials, or next-generation ingredients — building around scientific IP and R&D.
I may already have grant funding, a scientific advisory board, or a technically complex cap table with founders and early contributors.
I am preparing for a fundraise and need to secure SEIS Advance Assurance urgently — but I know the way my company is structured must clearly demonstrate risk-to-capital for HMRC.
Written by Elena Suciu
Elena Suciu is the Founder of The CFO Stack and Managing Director of the RSVP Business Angel Club. She has structured SEIS and EIS Advance Assurance applications for deep tech, biotech, foodtech and climate-tech founders across the UK and EU — with a focus on translating scientific and IP-heavy businesses into HMRC-aligned, investor-ready submissions.
Her work sits at the intersection of CFO-grade financial structuring, investor diligence and HMRC's risk-to-capital framework — the same lens applied to every guide and assessment published on this site.
SEIS eligibility — questions founders ask
Direct answers to the most common questions on SEIS eligibility, the risk-to-capital condition and HMRC Advance Assurance.
01What are the SEIS eligibility criteria in the UK?
02How do I know if my startup qualifies for SEIS?
03Can a deep tech or biotech company qualify for SEIS?
04Does grant funding affect SEIS eligibility?
05What is the SEIS risk-to-capital condition?
06How long does HMRC SEIS Advance Assurance take?
07Why do SEIS applications get rejected?
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