Startup due diligence in the UK: how to check a company before you invest
Tero team
The team behind Tero
3 min read
Updated 5 August 2026
Due diligenceRegistry filings
Key takeaways
- Due diligence is verification, not opinion-forming. The job is to check what the company claims against what the official record shows: Companies House, the FCA register, the courts, the Gazette and sanctions lists.
- The filings price the round, not the deck. An SH01 filing states the shares issued and the price paid; multiplied out, that is the valuation investors actually paid, and it does not always match the number in the press release.
- Most red flags are free to find. Dissolved co-founders' companies, disqualified directors, charges over assets, strike-off notices and county-court judgments are all on public registers that cost nothing to search.
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Companies HouseFCAGazetteCourtsSanctions
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Due diligence on a startup is often described as an art. Most of it is not. Before any judgement about markets or founders, there is a mechanical layer: checking that what the company says about itself matches the official record. In the UK that record is unusually rich, public, and mostly free. This guide is the staged process for working through it: practical due diligence for startups, using the UK's public record.
Stage one: the company as the register sees it
Start with the Companies House profile. Every UK company has one, and it takes two minutes to read properly.
Incorporation date and registered office. Does the corporate age match the story? A "founded 2019" pitch from a company incorporated eight months ago needs an explanation (there may be a good one, such as a restructure or a holding company, so ask).
Status and filings. Active, or with strike-off notices? Are accounts and confirmation statements filed on time? Persistent lateness is an operational signal, not a technicality.
Officers and PSCs. Who actually controls the company? The people with significant control are not always the people on the website.
Charges. A registered charge means a lender has security over company assets. Fine when it is a venture-debt facility everyone knows about; less fine when it is undisclosed.
Stage two: the money, and what the filings say the company is worth
This is the stage almost everyone skips, because it involves reading PDFs. It is also where the most expensive surprises live.
When a UK company issues new shares it files an SH01 stating how many shares were allotted and the price paid per share. Multiply price by the total share count and you have the implied valuation of that round. That is the number investors actually paid, as filed, and it can differ from the press release. Comparing the two is one of the highest-value checks an angel can run: raises that were announced but never filed, valuations quoted on a different basis, and rounds priced well below the last headline all show up here.
The annual confirmation statement (CS01) lists shareholders: the real cap table, at least once a year. Check the founder still owns what the deck implies they own.
Accounts, even the micro-entity kind, disclose more than people expect: net assets, cash at the small-company tier, sometimes headcount. A company claiming £1m in revenue whose balance sheet shows £40,000 of net assets deserves a follow-up question.
When a UK company issues new shares it files an SH01 stating how many shares were allotted and the price paid per share. Multiply price by the total share count and you have the implied valuation of that round. That is the number investors actually paid, as filed, and it can differ from the press release. Comparing the two is one of the highest-value checks an angel can run: raises that were announced but never filed, valuations quoted on a different basis, and rounds priced well below the last headline all show up here.
The annual confirmation statement (CS01) lists shareholders: the real cap table, at least once a year. Check the founder still owns what the deck implies they own.
Accounts, even the micro-entity kind, disclose more than people expect: net assets, cash at the small-company tier, sometimes headcount. A company claiming £1m in revenue whose balance sheet shows £40,000 of net assets deserves a follow-up question.
Stage three: the people
Stage four: the claims in the deck
Traction claims can often be tested against independent data: web traffic against search and traffic datasets, app claims against store rankings, hiring claims against live job listings, "partnership" claims against the partner's own announcements. The pattern to watch is a deck whose every number sits at the optimistic edge of what the public data supports. One inflated number matters less.
Red flags that should end the conversation
How long should this take?
Done by hand, a thorough pass over the sources above takes the better part of a day, which is why most angels do a fraction of it. Tero runs the full battery (registry, filings, valuation history, founders, courts, sanctions, digital footprint) in about fifteen minutes, with every claim traced to its source. You can check any UK company free right now, see a full example report, or start with the 12-source checklist if you prefer to run the process yourself. Information, not investment advice.
From the register
See it on a real filing history
Three UK companies whose priced rounds Tero has read from Companies House, with implied valuation at each allotment.
Questions this guide answers
- What is startup due diligence in the UK?
- Checking what a company claims about itself against the official record: Companies House, the FCA register, the courts, The Gazette and the sanctions lists, then testing the deck's claims against independent data.
- How do I check a UK startup's valuation?
- Read its SH01 filings at Companies House. Each states the shares issued and the price paid; multiplied by the shares in issue, that is the valuation investors actually paid, which may not match the press release.
- What red flags should end the conversation?
- A material gap between the filed and pitched valuations with no explanation, a disqualified or sanctioned person near the company, an active strike-off notice or winding-up petition, or a cap table where the founders no longer hold a meaningful stake.
- How long does thorough due diligence take?
- The better part of a day by hand, across the registers, the filings, the founders, the courts and the digital footprint. Tero runs the same battery in about fifteen minutes.
Tero runs these checks automatically.
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