- SEIS advance assurance is HMRC’s pre-approval confirming your company likely qualifies for the Seed Enterprise Investment Scheme, giving investors confidence before they commit funds.
- To qualify, your company must be UK based, under three years old, employ fewer than 25 people, and hold gross assets below £350,000 at the time of share issue.
- HMRC takes 15 to 45 working days to respond, so submit your application one to two months before you need to close investment.
SEIS advance assurance is HMRC’s pre-approval that your company is likely to qualify for the Seed Enterprise Investment Scheme, giving investors confidence before they commit money. You apply online through GOV.UK by submitting a business plan, financial forecasts, and details of at least one named investor, with HMRC typically responding in 15 to 45 working days.
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. Sleek’s SEIS and EIS advance assurance service prepares and submits everything HMRC needs.
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 is 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 proves to those investors that 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.
Why do investors ask for advance assurance?
Investors ask for advance assurance because it removes 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. Platforms like Crowdcube and Seedrs will not list a round without it. Angel syndicates routinely refuse to proceed until the certificate lands.
Who is eligible for SEIS advance assurance?
Your company is eligible for SEIS advance assurance if it is UK based, less than three years old, employs fewer than 25 full-time equivalent staff, and holds gross assets below £350,000 immediately before the share issue. You must also be carrying on a qualifying trade and not be controlled by another company.
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 | Below £350,000 before share issue |
Maximum raise under SEIS | £250,000 lifetime cap |
Investor stake per company | Maximum 30% shareholding |
Use of funds | Within 3 years of share issue |
A handful of trades are excluded entirely, including property development, financial activities, legal services, and farming. The full excluded list is published in HMRC’s venture capital schemes guidance on GOV.UK.
If you are 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, three-year financial forecasts, your latest accounts (if available), a copy of your memorandum and articles of association, your pitch deck, and details of at least one named potential investor. HMRC will not accept 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 is the document checklist HMRC expects:
- Business plan covering products, market, team, and growth strategy
- Financial forecasts for at least three years, including profit and loss, cash flow, and balance sheet
- Latest statutory accounts, if your company has filed any
- Memorandum and articles of association
- Pitch deck or investor presentation
- Companies House registration details
- Details of any previous SEIS, EIS, or other state aid received
- Names and contact details of at least one potential investor
HMRC officers read hundreds 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 do not need an accountant or solicitor to submit it, though most founders use one to avoid common rejection triggers.
The process runs in five clear 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, 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. Submit through the official venture capital schemes advance assurance portal.
- Respond to HMRC questions. Most applications get at least one follow-up query. Reply quickly and clearly to avoid delays.
If you would rather outsource the entire process, Sleek’s team prepares the documents, drafts the cover letter, and handles HMRC correspondence on your behalf.
How long does SEIS advance assurance take?
SEIS advance assurance takes between 15 and 45 working days from submission, depending on HMRC workload and the quality of your application. Clean, well-structured applications with no follow-up queries tend to come back inside three weeks. Applications with missing information or unclear trade descriptions can stretch past two months.
You should apply at least one to two months before you need the certificate. Investors will not transfer funds without it, and lead times have lengthened since 2023 as HMRC has taken on a larger volume of applications.
What does the SEIS advance assurance certificate look like?
The SEIS advance assurance certificate is a one to two page letter from HMRC stating that, based on the information provided, the company appears to meet the SEIS conditions at the time of writing. It names the company, references the proposed share issue, and is signed by an HMRC officer.
The certificate is not a guarantee. HMRC reserves the right to 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. Rejection rates have climbed since 2018, with HMRC publicly stating it will not process speculative applications.
The common reasons for refusal are well known and avoidable.
- No named investor. This is the most frequent reason. HMRC will not process applications without a real, identifiable investor expressing intent.
- Excluded trade. Property, finance, legal services, and similar activities are blocked outright.
- 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 used for 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 most growing companies do. You complete a single GOV.UK form and tick the boxes for both schemes, allowing you to use SEIS for the first £250,000 raised and EIS for subsequent rounds. HMRC issues a combined assurance letter covering both.
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 for maximum investor appeal.
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. The SEIS1 must be filed after the company has been trading for at least four months or has spent 70% of the funds raised, whichever comes first.
Once HMRC approves the SEIS1, it sends back authority to issue SEIS3 certificates to your investors. They use these to claim their tax relief through their personal tax return. The compliance process is where most companies trip up, because the timing and paperwork are tightly defined.
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 has prepared hundreds of successful applications and knows exactly what triggers a refusal.
We work with founders at every stage, whether you are 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.
Disclaimer: The preceding information is not legal advice. This content is aimed to provide general guidance. For more formal or legal advice, contact Sleek directly.
450,000
businesses worldwide.
from 4,100+ reviews.
satisfaction rate from
16,000 surveyed clients.
FAQs on SEIS advance assurance
Is SEIS advance assurance mandatory?
No. SEIS advance assurance is not legally required, and you can issue SEIS qualifying shares without it. In practice, most UK angel investors, syndicates, and crowdfunding platforms refuse to 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 have not yet generated income. HMRC does not 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.
How many investors do you need for an SEIS advance assurance application?
You need at least one named potential investor with contact details and an indication of how much they intend to invest. HMRC introduced this requirement in 2018 to stop speculative applications. The investor does not need to have committed funds yet, but they must be real, identifiable, and aware their name is being submitted to HMRC.
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 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 rate usually justify the fee, particularly when investment timing is tight.
View more
What happens if HMRC asks follow-up questions about your SEIS application?
HMRC routinely sends follow-up queries on a large share of applications, asking for clarification on trade activity, use of funds, or group structure. Respond in writing within 14 days, addressing each point directly with supporting evidence. Slow or vague replies extend processing time significantly. Most applications that receive queries still succeed, provided the responses are clear and consistent with the original submission.
Can AI startups qualify for SEIS advance assurance?
Yes. AI startups generally qualify, since software development and technology services are not 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.
