- Apply online via GOV.UK with a business plan, forecasts and investor details.
- HMRC aims to reply within 15 working days, or 40 for complex cases.
- Most first-time applicants must name at least one potential investor.
Here’s how to apply for SEIS advance assurance step by step: you submit HMRC’s online form through GOV.UK with a business plan, financial forecasts, and details of at least one named investor, and HMRC aims to respond within 15 working days (40 for complex cases). Advance assurance is HMRC’s pre-approval that your company is likely to qualify for the Seed Enterprise Investment Scheme, and Sleek’s SEIS/EIS advance assurance service prepares and submits everything HMRC needs.
Most early-stage founders apply one to two months before closing a round, because investors increasingly expect to see assurance in writing before transferring funds. This guide walks through the SEIS advance assurance application process, from eligibility checks to HMRC’s follow-up questions.
What is SEIS advance assurance?
SEIS advance assurance is a written confirmation from HMRC that your company appears to meet the conditions of the Seed Enterprise Investment Scheme, allowing your investors to claim up to 50% income tax relief on their investment. It’s not a guarantee, but it carries significant weight with sophisticated investors, angel networks, and crowdfunding platforms.
The scheme exists to help early-stage UK companies raise capital by offering generous tax breaks to individual investors. Advance assurance is the document that shows those investors HMRC has reviewed your structure and trade and sees no obvious reason to refuse relief later.
You can read more about how the relief itself works in our guide to SEIS tax relief and how it works, or about raising money with SEIS more broadly.
Why do investors ask for advance assurance?
Investors ask for advance assurance because it reduces the risk that HMRC later refuses their tax relief claim, which can cost them 50% of their investment in lost benefits. Without it, an investor has only your word that the company qualifies.
For most angel and seed-stage rounds in the UK, advance assurance has become a baseline requirement rather than a nice-to-have. Many crowdfunding platforms and angel syndicates expect to see it before a round goes ahead.
Who is eligible for SEIS advance assurance?
Your company is eligible for SEIS advance assurance if it’s UK based, less than three years old, employs fewer than 25 full-time equivalent staff, and holds gross assets of no more than £350,000 when the shares are issued. It must also be carrying on a qualifying trade and not be controlled by another company, in line with HMRC’s SEIS company conditions.
The full eligibility criteria sit across HMRC’s published rules and the Income Tax Act 2007. The key thresholds you need to know are summarised below.
| Requirement | Threshold |
|---|---|
| Company age | Under 3 years of trading |
| Employees | Fewer than 25 full-time equivalent |
| Gross assets | No more than £350,000 when shares are issued |
| Maximum raise under SEIS | £250,000 lifetime cap |
| Investor stake per company | Maximum 30% shareholding |
| Use of funds | Within 3 years of share issue |
Some trades don’t qualify if they make up more than 20% of your activity, including property development, legal and financial services, and farming. The full list sits in HMRC’s non-qualifying trades guidance on GOV.UK.
If you’re not sure whether SEIS or EIS is right for you, our guide on the difference between SEIS and EIS breaks down which scheme suits which stage of business.
What documents do you need for an SEIS advance assurance application?
You need a business plan, financial forecasts, your latest accounts (if available), your memorandum and articles of association, your register of members, your pitch deck, and details of at least one named potential investor. Unless you’ve raised under a venture capital scheme before, HMRC won’t consider an application without a real investor on file.
The named investor requirement trips up a lot of founders. HMRC introduced it in 2018 specifically to stop speculative applications from companies with no live fundraising activity. You need their name, address, and an indication of how much they intend to invest.
Here’s the document checklist HMRC expects:
- Business plan covering products, market, team, and growth strategy
- Financial forecasts, including profit and loss, cash flow, and balance sheet
- Latest statutory accounts, if your company has filed any
- Memorandum and articles of association
- Register of members, dated the day you apply
- Pitch deck or investor presentation
- Company registration number and corporation tax UTR
- Details of any previous SEIS, EIS, or other state aid received
- Names and addresses of at least one potential investor
Tip: HMRC officers read a lot of these applications. Plain English wins. Cut the buzzwords from your business plan and lead with what the company sells, who buys it, and how the money raised will be spent.
How do you apply for SEIS advance assurance?
You apply for SEIS advance assurance by completing the online form on GOV.UK and uploading the supporting documents in a single submission. The application is free, and you don’t need an accountant or solicitor to submit it, though many founders use one to avoid common rejection triggers.
The SEIS advance assurance application process runs in five steps.
- Confirm eligibility. Run through the company age, employee count, gross assets, and trade restrictions before you start.
- Gather documents. Pull together the business plan, forecasts, accounts, articles, register of members, and investor details listed above.
- Identify a named investor. Speak to an angel, fund, or platform and get their written commitment to consider your round.
- Complete the GOV.UK form. Sign in and submit through the official venture capital schemes advance assurance portal, quoting your company registration number and UTR.
- Respond to HMRC questions. HMRC may come back with follow-up queries, so reply quickly and clearly to avoid delays.
If you’d rather outsource these SEIS application steps, Sleek’s team prepares the documents, drafts the cover letter, and handles HMRC correspondence on your behalf.
How long does SEIS advance assurance take?
HMRC aims to respond to most applications within 15 working days, and within 40 working days for complex cases. Clean, well-structured applications with no follow-up queries tend to come back inside three weeks, while applications with missing information or unclear trade descriptions can stretch to two months.
Getting the SEIS application steps right first time is the simplest way to stay at the quicker end. Apply at least one to two months before you need the assurance, because many investors won’t transfer funds without it.
What does the SEIS advance assurance certificate look like?
SEIS advance assurance arrives as a letter from HMRC stating that, based on the information provided, the proposed share issue is likely to meet the SEIS conditions. It names the company and references the proposed share issue, and you can show it to your investors.
The letter isn’t a guarantee. HMRC can still refuse relief later if circumstances change, if the information turned out to be inaccurate, or if the company breaches a SEIS condition after the share issue. That said, investors treat it as the strongest signal available short of the SEIS3 compliance certificate that follows the actual share issue.
Why does HMRC reject SEIS advance assurance applications?
HMRC rejects SEIS advance assurance applications when the company falls outside the eligibility criteria, when the business plan is vague, or when no named investor is included. Since 2018, HMRC has said it won’t consider speculative applications from companies with no live fundraising.
The common reasons for refusal are well known and avoidable.
- No named investor. A first-time application without a real, identifiable investor expressing intent won’t be considered.
- Excluded trade. Property development, legal and financial services, and similar activities count against you once they’re more than 20% of the trade.
- Excessive gross assets. Companies over the £350,000 threshold at the point of share issue are refused.
- Group structure issues. If your company is a subsidiary or has a parent company, you almost always fall outside SEIS rules.
- Use of funds unclear. HMRC wants to see that money raised will be spent on a qualifying trade within three years.
- Previous state aid not declared. Grants, R&D credits, and other funding must be disclosed.
We cover the most common application mistakes in detail in our guide on SEIS and EIS common pitfalls.
Can you apply for SEIS and EIS advance assurance at the same time?
Yes, and many growing companies do. You complete a single GOV.UK form and select both schemes, allowing you to use SEIS for the first £250,000 raised and EIS for later rounds.
This dual approach is standard for companies raising more than £250,000 in their first round, or planning a Series A within the SEIS three-year window. Our breakdown of SEIS and EIS benefits for founders and investors explains how to sequence the two schemes, and our guide to claiming EIS relief covers what EIS investors do once the shares are issued.
What happens after you receive advance assurance?
After receiving advance assurance, you can close your round, issue shares to investors, and then file the SEIS1 compliance statement with HMRC. You can only submit the SEIS1 once the company has carried on its new qualifying trade for at least four months or spent at least 70% of the money raised.
Once HMRC approves the SEIS1, it sends back authority to issue SEIS3 certificates to your investors, who use them to claim their tax relief through their personal tax return. The compliance process is where many companies trip up, because the timing and paperwork are tightly defined; our guide to compliance after funding covers the deadlines.
How Sleek helps with SEIS advance assurance
Sleek prepares your advance assurance application end to end, from drafting the business plan summary HMRC wants to see, to packaging the financial forecasts, to handling the back-and-forth once submission is in. Our team knows what triggers a refusal and builds the application to avoid it.
We work with founders at every stage, whether you’re pre-revenue raising your first £150,000 or scaling toward an EIS round. The fixed fee covers preparation, submission, and follow-up correspondence with HMRC, and once you’ve raised, a limited company accountant keeps your filings and SEIS compliance on track.
Get your SEIS advance assurance application handled by experts
FAQs on how to apply for seis advance assurance step by step
Is SEIS advance assurance mandatory?
No. SEIS advance assurance isn’t legally required, and you can issue SEIS qualifying shares without it. In practice, many UK angel investors, syndicates, and crowdfunding platforms won’t invest without seeing the HMRC letter first, treating it as protection against losing their 50% tax relief later. Skipping advance assurance is technically possible but usually closes more doors than it opens.
Can pre-revenue startups get SEIS advance assurance?
Yes. Pre-revenue startups are the most common applicants for SEIS advance assurance, since the scheme was designed for very early-stage companies that haven’t yet generated income. HMRC doesn’t require you to be trading or earning revenue, only that you intend to carry on a qualifying trade and can show how the funds raised will be deployed within the required timeframe.
Do you need named investors if you're raising through a crowdfunding platform?
No, you give different evidence instead. If you’re raising through a crowdfunding platform, HMRC wants evidence that the platform has accepted your proposal and will keep working with you, and if you’re using a fund manager or business promoter, you need evidence they’ve agreed to act on your behalf. Companies listed on AIM don’t need to give investor details at all, while those planning to list must give the name and registration number of their nominated adviser.
Can overseas founders apply for SEIS advance assurance?
Yes, provided the company is incorporated in the UK and has a permanent establishment here. Founders themselves can be non-UK residents, but the business must operate from a UK base, employ UK staff, or have UK trading activity, and meet all standard SEIS conditions. Our guide on starting a UK company as an Australian resident explains the setup requirements.
Should you use an accountant for SEIS advance assurance applications?
Most founders benefit from using a specialist, even though the application is free to submit yourself. An experienced startup accountant or adviser drafts the business plan in HMRC’s preferred format, flags trade or structure issues before submission, and handles follow-up queries. The faster turnaround and lower rejection risk usually justify the fee, particularly when investment timing is tight.
What happens if HMRC asks follow-up questions about your SEIS application?
HMRC may ask for clarification on trade activity, use of funds, or group structure before it reaches a view. Respond in writing, addressing each point directly with supporting evidence, because slow or vague replies extend processing time. Once HMRC has given its opinion, it’ll engage in no more than two rounds of correspondence about the investment, so get your answers right first time.
Can AI startups qualify for SEIS advance assurance?
Yes. AI startups generally qualify, since software development and technology services aren’t on HMRC’s excluded trades list. The company still needs to meet the standard tests on age, employee count, gross assets, and use of funds. HMRC pays close attention to whether the business is genuinely trading or simply holding intellectual property, so a clear commercial roadmap is essential, and our investor scheme FAQs cover the share questions that usually follow.
