Here's the uncomfortable truth about early-stage diligence: at the point where it matters most, there's almost nothing to audit. A seed company has a few months of revenue if you're lucky, a product that changes weekly, and a market that doesn't exist yet in the form the founders are betting on. You can't model your way to a verdict. So the real question a syndicate is trying to answer isn't "do the numbers hold up" - it's "are these the right people, chasing the right thing, on terms I can live with."
That's what due diligence at this stage actually is: a structured attempt to be wrong less often. Not a guarantee, not a clean bill of health. A way of surfacing the obvious problems before the money's gone and turning a gut feeling into something you can defend.
Who actually does the diligence?
In a syndicate, the lead does the bulk of it. That's the whole bargain. The lead sources the deal, negotiates the terms and runs the checks; the backers come in behind with smaller cheques on the back of that work. By the time a deal reaches you, the lead has usually known the founders for a while, taken the meetings, and formed a thesis. What lands in your inbox is the write-up - the deal memo - not a blank page.
On a platform, some of this is institutionalised: there may be an investment team, a standard checklist, a data room. With a solo lead it's more personal and more variable - which is exactly why the quality of the lead is itself something to assess. A thin memo from a lead who's "just got a good feeling" is telling you something. So is a careful one that names the risks out loud.
Following a lead is a decision in itself, not a substitute for one.
What does a syndicate actually check?
The work clusters into five areas. None of them is a box-tick; each is a place where a deal quietly falls apart.
The team
At seed, this is the single biggest line of inquiry, because the company will pivot several times and the people are the only thing that carries through. The lead is checking the founders' track record, whether they've worked together before, how they handle hard questions, and whether their split of equity and roles makes sense. Reference calls matter here more than anything on a slide. The polite phrase is "founder-market fit"; the blunt version is "do these specific people have any business winning this specific race."
The market and the product
Is the problem real, is it big enough to matter, and is anyone already solving it better? The lead probes the size of the opportunity, who the competitors are, and what would have to be true for this to become a large company rather than a small one. Alongside that sits whatever traction exists - early revenue, users, pilots, a waiting list, signed letters of intent. The point isn't that the numbers are big; at this stage they rarely are. It's whether there's a credible signal that someone, somewhere, wants this enough to pay for it.
The numbers, the legals and the cap table
Then the unglamorous half. How much runway does the round buy, and what does the company have to achieve before it needs to raise again? What are the burn rate and the basic unit economics, as far as they can be known? On the legal side, the lead checks that the company owns its intellectual property, that there are no nasty clauses buried in earlier agreements, and that there's no outstanding litigation or unpaid liability waiting to surface.
And the cap table: who already owns what. A messy ownership structure - too much gone to early backers, a departed founder still holding a big slice, an option pool that's about to dilute everyone - can sink an otherwise good company. This is where the round's term sheet and valuation get scrutinised, because the price you pay shapes every return that follows.
The tax position: SEIS and EIS
For UK angels, the tax treatment isn't a footnote - it changes the whole shape of the bet. So a careful lead checks it as part of diligence, not after the fact. The two questions are: does the company qualify for SEIS or EIS relief, and does the syndicate's structure let that relief reach the backers?
On the first, the signal to look for is HMRC advance assurance - a pre-investment indication from HMRC that the company looks eligible. It isn't a guarantee, and final relief still depends on the SEIS3 or EIS3 certificate the company issues after the round, but its absence is a flag worth asking about. The headline investor reliefs are fixed: SEIS gives 50% income tax relief on up to £200,000 invested per tax year, with a three-year minimum hold; EIS gives 30% on up to £1,000,000 per tax year - or £2,000,000 where at least £1,000,000 goes into knowledge-intensive companies - also with a three-year hold. The company-side ceilings (gross assets, annual and lifetime raise caps, age and employee limits, and the knowledge-intensive variations) move periodically, so the current figures live in HMRC's EIS guidance and the guidance for investors.
On the second, structure decides everything. If you invest through a nominee arrangement, you're treated as holding the shares yourself and can claim relief in the normal way. If the money goes through a special purpose vehicle that holds the shares, you own the vehicle rather than the company - and that usually breaks the SEIS/EIS chain. A lead who's done the work will tell you which one you're in before you commit. Investors generally need to be UK taxpayers to use the reliefs at all.
How the diligence reaches you: the deal memo
All of this is supposed to land in one document. The deal memo is the lead's case for the investment and the evidence behind it - the company and what it does, the team, the market, the traction, the round terms and valuation, the lead's own thesis and how much of their own money is going in, the principal risks, and the tax position. It's the single most important thing you read before deciding whether to follow.
Read it for what it leaves out as much as what it states. A good memo names the risks plainly and shows its working. A weak one reads like a pitch - all upside, no doubt, valuation asserted rather than reasoned. The amount the lead is personally committing is one of the more honest signals on the page: real money alongside yours concentrates the mind.
How to read a syndicate's diligence
Two things are worth holding in mind. First, angel diligence is fast and thin by necessity. A venture fund might spend months; a syndicate window is often a week or two, and the lead has done much of the work before you ever see it. That speed is a feature of the asset class, not sloppiness - but it means the verdict rests on judgement, not certainty.
Second, the lead's diligence reduces your work; it doesn't remove your responsibility. The lead is backing their thesis, and they keep their carry whether the deal works or not. The risk on your share is entirely yours. So treat the memo as a strong starting point, check the points that bear on your own tolerance for loss, and don't mistake a confident lead for a safe deal. Diligence narrows the unknowns. It can't make an early-stage company safe, because no early-stage company is.
That's not a reason to skip the work. It's the reason to do it with your eyes open - and, where it counts, with regulated advice.
Frequently asked questions
How long does a syndicate's due diligence take?
At the angel stage it is usually a matter of days to a few weeks, not the months a venture fund might spend. The lead has often already built a relationship with the founders and done much of the work before the deal is circulated, so by the time backers see a memo the heavy lifting is largely complete. The investment window itself - the period in which backers commit - is often only a week or two. The earlier the company, the thinner the evidence, so much of the work is judgement about people and market rather than auditing numbers that barely exist yet.
Does the syndicate lead's diligence replace my own?
No. The lead's work is a strong starting point, not a substitute for your own judgement. A lead reduces the work you have to do and brings access and pattern recognition you may not have, but they are investing their thesis, not yours, and they keep carry whether the deal works or not. Read the memo critically, check the points that matter to your own risk tolerance, and remember that following a lead is itself a decision. This is general information, not financial advice.
What is a deal memo in an angel syndicate?
A deal memo is the document a syndicate lead circulates to backers setting out the case for an investment and the diligence behind it. It typically covers the company and what it does, the team, the market, the traction so far, the round terms and valuation, the lead's own thesis and commitment, the main risks, and the tax position - including whether the company holds HMRC advance assurance for SEIS or EIS. It is the single most important thing a backer reads before deciding whether to follow.
Does due diligence check whether SEIS or EIS relief is available?
It should. A careful lead confirms the company holds HMRC advance assurance - the pre-investment indication that the company looks eligible - and that the syndicate's structure lets relief flow through to backers. A nominee arrangement, where you are treated as holding the shares yourself, normally preserves SEIS or EIS relief; an SPV that holds the shares itself often breaks it. Advance assurance is not a guarantee, and final relief depends on the SEIS3 or EIS3 certificate issued after the round. Investors usually need to be UK taxpayers to use the reliefs.
Can due diligence remove the risk from an angel investment?
No. Diligence narrows the unknowns and surfaces the obvious problems, but most early-stage companies still fail, and no amount of checking changes that. The point of diligence is to make sure you are taking a risk you understand and can afford to lose, not to make the risk disappear. Angel investing means putting illiquid money into companies that may not survive. This article is general information, not financial or investment advice; consider taking FCA-regulated advice before you invest.