Series A Data Room: What UK Investors Verify Before the Round Closes

A signed term sheet feels like the finish line. It's closer to the starting gun.

In the largest survey of venture capitalists I know of, the average deal took 83 days to close, and the average firm spent 118 hours on due diligence in that time. Those figures come from How Do Venture Capitalists Make Decisions?, by Paul Gompers, Will Gornall, Steven Kaplan and Ilya Strebulaev, and they're mostly US data from 2015 and 2016. The point travels well. Months pass between "yes" and money in the bank, and someone spends a lot of hours checking that everything you've said is true.

Most of those hours are spent in your data room. The deck got you the term sheet. The data room decides whether the round closes on the terms you agreed.

This guide is for UK founders getting ready for a Series A, and for the angels and advisers helping them. It goes through what investors verify, roughly in the order they verify it, the UK-specific checks (Companies House, SEIS and EIS, UK GDPR, copyright ownership), and the gaps that most often slow a round down. It isn't legal or tax advice. You'll want a solicitor for the round itself.

UK Series A investors use the data room to confirm what your deck claimed. They usually start with the cap table and corporate records, then check revenue against bank statements and contracts, intellectual property ownership, SEIS or EIS status, data protection and the sources behind your market claims. Founders who build the room before the term sheet close faster and with fewer surprises.

What Happens After the Term Sheet

After a term sheet is signed, the investor moves from deciding whether they like the company to confirming that it is what you said it is. Due diligence for early-stage companies is mostly about checking claims you've already made.

Jason Lemkin, the SaaStr founder and investor, sets out the difference neatly in a post on due diligence before and after a term sheet. Before it, a few customer calls ("Often just 2 or 3") and a basic look at the financials and model. After it, deeper customer calls, "Bank statements & deep financial review", and legal due diligence: former founders, the cap table, and whether the founders have enough unvested stock left.

His warning to founders is blunt: "If you have something to hide here, it will likely come out later. Post term sheet." He adds that it's worse when a signed term sheet falls apart than when a deal never gets that far.

Typically the investor's own team goes through the room first, looking for anything that would make the deal hard to justify to their investment committee, and lawyers and accountants then go deeper on their own areas. Underscore VC's Brian Devaney walks through what that process looks like from the investor's side, from more time with the founder to customer feedback, reference checks and a review of the key business risks:

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The deck and the data room are judged against different standards. A deck is allowed to be persuasive. The data room has to be accurate. Where the two disagree, the data room wins, and the investor starts wondering what else in the deck was persuasive rather than accurate.

One habit makes the whole process smoother. Keep a question log from the first day of due diligence: every question the investor asks, who asked it, the answer you gave, and the document that supports it. Answer in writing where you can, and have one person on your side own the log. Questions tend to come back in slightly different forms from different people, and a log stops you giving two answers to the same question. It also becomes the first draft of your disclosure if the lawyers ask for one.

Cap Table and Corporate Structure

The cap table is usually checked first, because a broken cap table can make a deal impossible to close regardless of how good the revenue looks. Investors need to know exactly who owns what, and that the public record agrees.

The Companies House point is newer than many founders realise. Identity verification became mandatory for directors and people with significant control from 18 November 2025, after a voluntary period that began on 8 April 2025. An investor's lawyer will look at your company page. Make sure it's complete and current before they do.

The commonest cap table problem is a departed co-founder. Someone left early, kept a large stake, and there's no clear agreement about vesting or buying it back. That isn't always fatal, but it's always a negotiation, and it's one you'd rather have before a term sheet than after. Lemkin lists "ex-founder issues" as one of the first things legal due diligence looks for.

The option pool gets the same treatment. Investors will want to see that every grant was approved properly, that the paperwork for each one exists, and that the numbers on the cap table match the option agreements. If some early team members were promised options in an email and never got the documents, sort that out now. A promise that isn't on the cap table is exactly the kind of surprise that slows a round.

SEIS and EIS Paperwork

If your round relies on SEIS or EIS tax relief, investors will check the paperwork early, because the relief can be a large part of the return for UK angels. That means the advance assurance letter, the application behind it, and anything that has changed since.

Advance assurance is HMRC's view that an investment is likely to qualify. It isn't a guarantee. HMRC's guidance says that if you get it, HMRC sends a statement that "the investment is likely to qualify", that investors should still "conduct their own due diligence", and that if things change before your compliance statement, "the assurance will no longer apply."

The application asks for your business plan and financial forecasts, your latest accounts, your articles, a copy of the register of members and the latest draft of any investor-facing documents. In other words, HMRC has seen a version of your deck. If the deck has changed a lot since, make sure the story still matches.

HMRC's own statistics show how widely the schemes are used, and that approval isn't automatic. In the May 2026 release, 3,735 companies raised £1,575 million under EIS and 2,430 companies raised £276 million under SEIS in the 2024 to 2025 tax year. Of the advance assurance requests received in 2025 to 2026, HMRC had approved 72% for EIS and 76% for SEIS by March 2026.

If you're not sure what SEIS covers or how advance assurance works, Vestd's Guy Kaufman gives a clear four-minute overview, including how to apply:

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Revenue Verification

The deck says what your revenue is. The data room has to prove it. Investors check revenue against sources you don't control, and they won't treat a self-reported spreadsheet as enough on its own.

There's a UK-specific reason for that. Most start-ups don't publish revenue anywhere. Under the small company rules on GOV.UK, a company with turnover of £15 million or less can usually choose whether to send its profit and loss account to Companies House, and micro-entities can file just a simplified balance sheet. So the investor can't check your revenue from public records. They'll check it from yours.

Two problems come up again and again. The first is recurring revenue that quietly includes one-off work, like set-up fees or consulting, which makes the recurring figure look bigger than it is. The second is a revenue figure that doesn't reconcile with the bank. Small timing differences are normal and easy to explain. An unexplained gap triggers a full recount, and the trust damage is often worse than the number.

Expect questions about customer cohorts as well as totals. A bridge that shows how revenue moved each month, split into new customers, expansion, contraction and churn, tells an investor far more than a single ARR figure. If you've grown mainly by adding new logos while older customers quietly shrink, the bridge will show it, so it's better that you've looked at it first and can explain what's happening.

Customer concentration gets a look too. If one or two customers make up a large share of revenue, investors will want to see those contracts, the renewal dates and the notice periods. That's no reason to hide them. Put them at the top of the commercial folder with a short note on the relationship.

My advice is to do the reconciliation yourself before the room opens, write a one-page note explaining any differences, and put the note in the room. Investors respect a founder who has already found and explained the awkward bits.

Intellectual Property and People

Investors need to be sure the company owns what it's being valued on. The key question is simple: was everything important created by the company's employees, or under a written assignment to the company?

UK copyright rules make this matter. GOV.UK's guidance on copyright ownership says that work made by an employee in the course of their job generally belongs to the employer. But a freelancer or independent contractor will usually keep the copyright in what they produce, "unless there is a contractual agreement to the contrary." For commissioned work, the creator is the first owner unless you "otherwise agree it in writing."

That catches a lot of start-ups. The first version of the product was built by a founder before the company existed, by a freelance developer, or by an agency. Unless those people signed assignments, the company may not own its own code. Investors look for:

• IP assignments signed by every founder, covering work done before incorporation.
• Contractor and agency agreements with clear assignment clauses.
• Employment contracts with standard IP provisions.
• An open-source review, so nothing in the product carries a licence that conflicts with how you sell it.

One case deserves special care. If a founder built the first version while employed somewhere else, the former employer may have a claim, depending on their contract and what was built. If that applies to you, get legal advice before the data room opens. It's much easier to fix on your own timetable.

Gaps like these tend to surface at the worst moment. One founder described on r/startups in October 2025 what that felt like:

Team and employment

At Series A the team is still a large part of the investment case, so investors check it in two ways: desk research (LinkedIn, past companies, press coverage, references) and documents in the room. They'll want employment contracts for key people, founder vesting schedules, any non-compete or non-solicitation obligations from previous jobs, and confirmation that your technical lead is employed by the company rather than contracted to it.

Data Protection and Compliance

At seed, compliance checks are often light. At Series A they get much more thorough, especially if you handle personal data, sell into a regulated sector or have customers outside the UK.

Expect questions about your privacy notice, records of processing, data processing agreements with customers and suppliers, any correspondence with the ICO or another regulator, your insurance, and your board minutes. Investors read minutes for decisions that contradict what founders have said, so make sure they're complete and actually signed.

The data room itself is a data protection question too. If you put customer lists, employee files or contracts with personal data in the room, you're sharing personal data with a third party. The ICO's data sharing code has a section on due diligence, written mainly for mergers and acquisitions, that says "You must comply with the data protection principles, and document your data sharing." The safe habit is to share summaries or anonymised data first, give detail only to the people who need it, and keep a log of what was shared.

Market Size and Competitive Claims

Market claims are checked throughout due diligence, because they underpin the valuation. Investors don't expect you to have commissioned original research. They do expect every market number in the deck to trace to a document they can open, for your market, for a recent year.

Bottom-up estimates are worth the effort. Underscore VC's guide to the bottom-up market size slide puts the case against top-down figures plainly: "the data is often arbitrary and unreliable." Count the customers you could realistically sell to, multiply by what they'd pay, and show your working.

The most damaging failure here is what I'd call source laundering. A deck cites a press release, which cites a report, which the investor buys or finds and discovers doesn't say what the deck claims. One collapsed number like that costs you credibility on every other number. I go through how investors trace these in how investors verify startup claims, and the free Series A claim checklist turns it into 23 checks you can run yourself.

What a Ready Data Room Looks Like

A ready data room answers questions before the investor asks them. That comes from clear organisation and early disclosure. Adding more documents doesn't help on its own.

Most UK Series A rounds use documents based on the templates from UK Private Capital, the industry body formerly known as the BVCA. Its model documents for early-stage investments say they "have been drafted for use on a Series A funding round", and include a subscription agreement, a shareholders' agreement and articles. The subscription agreement contains warranties, formal statements about the company that the investors rely on. When the templates were updated in 2025, Burges Salmon's summary listed "Revised intellectual property, business systems and data protection warranties" among the changes.

That's a useful way to think about the room. Every warranty you'll be asked to give is a statement about the company, and the room is where you show it's true. Here's a folder structure that maps to the checks above:

Slidebean's walkthrough covers the same ground from a founder's point of view, and links to templates for the financial model and cap table:

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Build it before you need it

The data room should be largely complete before you sign a term sheet. Founders who start building it afterwards spend the first weeks of due diligence chasing documents, which looks disorganised at exactly the moment the investor is judging how you run things.

The easiest way to have a ready room is never to let it fall behind. Sign IP assignments at incorporation. Keep signed copies of every material contract in one place. Produce monthly management accounts from early on. Minute every board meeting properly. None of that is exciting, and all of it saves weeks later.

Think about access too. Most data room tools let you control who sees which folders, and show you who opened what. Use both. Give the investor's team the full room, give outside advisers the folders they need, and keep anything with personal data in a folder you open last. When you see a folder being read closely, expect questions about it soon.

Make the Deck and the Data Room Agree

The single most useful thing you can do before opening the room is a consistency pass: take every claim in the deck and find the document in the room that supports it. If a claim has no document, either add one or change the claim.

It sounds obvious. It's also where most of the awkward due diligence questions come from. A deck that says "120 customers" next to a customer list with 104 rows. A team slide that calls someone a co-founder who doesn't appear on the cap table. A growth chart that uses a different month-end from the management accounts. None of those is dishonest. Each one costs an afternoon of explanation and a little trust.

Do the same check outwards. Your website, LinkedIn pages, Companies House record and any press coverage should match the deck on the basics: what you sell, who to, how many people you employ, who leads the company. Investors can look at all of them, and so can the AI tools some of them use for a first read.

A claims log makes this manageable. One row per claim, with the slide, the source document, the date and who checked it. I walk through building one in how to fact-check a pitch deck, and you can see how we test a single claim end to end in how Release Assurance checks a claim.

Errors That Kill Deals Before Close

The failures that most often break a signed term sheet are surprises. Bad news, disclosed early, usually isn't one of them. Investors can price a known problem. A problem they discover makes them question everything else.

So if you know about a problem, disclose it early and in writing, with the facts and what you're doing about it. A short note in the relevant folder (for example, that an old contractor agreement had no IP assignment, that a confirmatory assignment has now been signed, and a copy) turns a potential deal-breaker into a resolved item. The same fact discovered by the investor's lawyer reads very differently.

1. Revenue that doesn't reconcile with the bank. Any unexplained gap leads to a recount of every revenue figure, and often to a lower valuation.
2. Unexplained equity on the cap table. Usually a departed co-founder with a large stake, no buyback and no agreement governing it.
3. IP the company doesn't own. Code or designs created by a founder, freelancer or agency without a signed assignment.
4. Market claims that collapse when checked. A cited figure that turns out to measure something else, in another country or another year.
5. SEIS or EIS paperwork that doesn't match the round. Advance assurance that's missing, out of date, or based on a different plan, when investors were counting on the relief.
6. Governance gaps. Missing board minutes, unsigned resolutions, or decisions that contradict what founders have said.

Governance gaps can catch out even the best-known investors. When FTX collapsed in November 2022, Dan Primack, now a business editor at Axios, pointed out something about two of Sequoia's largest bets:

That's an outlier, and a very late-stage one. At Series A, the lesson runs the other way. Investors who've watched cases like that are more likely to ask about board minutes and financial controls than less.

The UK Funding Backdrop

UK investors are choosing from a tighter market than a few years ago, which makes a clean data room more valuable, not less. Fewer deals means more scrutiny on each one.

The British Business Bank's Small Business Equity Tracker says UK smaller businesses raised £12.3 billion of equity across 2,002 deals in 2025. Investment fell 4% on 2024, and deal numbers fell 17%. Seed-stage deal numbers fell 27%, more than any other stage, while growth-stage investment rose 10% to £5.7 billion. AI companies took a record 44% of all investment.

The bank's July 2026 announcement adds that early-stage deals at venture stage were 13% lower in 2025, and that London's share of UK equity investment fell from 60% to 57%. So investment is spreading a little beyond London, but every round is still competing for attention. A data room that answers questions on day one is a real advantage.

It's also worth keeping the bigger picture in mind. Plenty of companies that raise a seed round never raise a Series A, for reasons that have nothing to do with paperwork. I've looked at what the most quoted figures actually measure in what the 43% startup failure rate really means. If you've reached a Series A term sheet, you've already done the hard part. Don't let an unsigned assignment or an unreconciled spreadsheet be what slows it down.

Where ThriveFinity Fits

Every claim in your deck becomes a question in due diligence. We check those claims against named, dated sources before the investor does, so the deck and the data room tell the same story.

• First Signal (free, under an hour): one claim or one positioning check, to see the method before you pay anything.
• Release Assurance Pack (£699, 3 business days): every headline claim in your deck checked against primary sources, with evidence graded A to E, weak claims rewritten and a signed Assurance Note.
• Release Assurance Suite (£1,749, 5 business days): three or more documents, such as the deck, a one-pager and your website, checked against each other for consistency, with a 72-hour window to fix flagged items.

The full scope is on the Release Assurance page, and our methodology explains how we grade sources. Investors who want the same checks on a company they're backing can see our diligence services for investors. If you'd rather the founder commissioned it, you can refer a founder at no cost to you. We don't pay or accept referral fees.

We're not the right choice for legal due diligence, a financial audit, tax advice on SEIS or EIS, or building the data room for you. You need a solicitor, an accountant and probably a tax adviser for those. What we do is narrower: we tell you which claims in your documents stand up to checking, and which don't.

Pranav Unni

Founder · ThriveFinity Connect on LinkedIn →

Pranav Unni is the founder and lead verifier of ThriveFinity. He reads and signs every paid deliverable personally, and writes about go-to-market decisions for established B2B companies.