What extra due diligence do institutional VCs run at Series A?
By SuLe · Updated 6 May 2026
Beyond the seed-stage basics, Series A investors commonly add management referencing, customer calls, technical or code review including open-source scans, financial-model interrogation, and specialist IP or regulatory diligence. It is a structured, multi-workstream exercise, and what it turns up feeds straight into your warranties, price and deal terms.
Key facts
- Series A diligence is a multi-workstream exercise — legal, financial, commercial and technical run in parallel.
- Common additions beyond seed: management referencing, customer calls, code review with open-source scans, financial-model interrogation, and specialist IP or regulatory diligence.
- Findings become price chips, warranty demands or escrow holdbacks — so gaps are expensive.
- A clean cap table reconciled to Companies House filings and complete IP assignments are the baseline.
- Preparing the data room before you start is the single biggest time-saver.
How is Series A diligence different from seed?
At seed, diligence is usually light — a look at the cap table, the key contracts, and whether the IP sits in the company. Series A is an order of magnitude deeper.
An institutional fund runs several workstreams at once: legal diligence on the corporate and contractual position, financial diligence on the numbers, commercial diligence on the market and customers, and technical diligence on the product. Each is often handled by a different team or adviser.
The output is not just a yes or no. It shapes the valuation, the warranties you give, and whether the fund asks for escrows or specific indemnities. [More: How is a Series A different from a seed round legally?]
What commercial and management checks do VCs add?
Two stand out. Management referencing means the fund speaks to people who have worked with you — sometimes former colleagues or co-investors — to test how you lead and deliver. It is about backing the team, not just the idea.
Customer calls, done with your consent, test whether your growth and retention story survives contact with the people actually paying you. A fund that hears lukewarm customers will price that in.
Line up supportive references and reference customers early. Being caught flat-footed here reads as a red flag, even when the underlying business is strong.
What technical and IP diligence should I expect?
At Series A, expect a technical or code review — often including automated open-source scans that check which open-source components you use and whether you comply with their licences. Restrictive licences in your codebase can create real problems, so know what you have shipped.
Specialist IP diligence checks the chain of ownership: that founders, contractors and agencies have all assigned their work to the company, and that nothing critical sits outside it. Regulated sectors add regulatory diligence on top.
Broken IP chains are one of the most common findings and one of the most damaging, because a buyer or investor needs certainty that the company owns what it sells. [More: What legal prep does a startup need before an exit?]
| Workstream | What it looks at | Common finding |
|---|---|---|
| Management referencing | How you lead and deliver | Gaps between story and references |
| Customer calls | Revenue and retention reality | Softer demand than pitched |
| Technical / code review | Product quality, open-source use | Licence non-compliance |
| Financial-model interrogation | Assumptions and unit economics | Optimistic or unsupported forecasts |
| IP diligence | Ownership chain | Unassigned contractor or founder IP |
| Regulatory diligence | Sector compliance | Missing licences or approvals |
How does the financial model get tested?
Investors interrogate the model behind your forecast, not just the top-line numbers. They probe how you built it, your unit economics, cohort retention, and how sensitive the outputs are to changes in key assumptions.
The goal is to see whether the plan is defensible or merely optimistic. A founder who cannot explain their own assumptions undermines confidence quickly, however good the headline growth looks.
Know your model cold before the process starts — the drivers, the weak points, and the evidence behind each assumption. Being able to defend it calmly is worth as much as the numbers themselves.
Worked example
Yusuf runs a logistics-software startup raising a £5m Series A. The lead fund runs four workstreams at once: legal, financial, commercial and technical.
Commercial diligence includes calls with five of his customers; two flag slow onboarding, which the fund raises in negotiation. Technical review runs an open-source scan and finds one component under a restrictive licence, prompting a warranty and a remediation plan. IP diligence discovers a former contractor never signed an assignment, so Yusuf secures a retrospective assignment before completion.
None of these sinks the deal, but each becomes a discussion point — a small price adjustment, a specific warranty, and a fix. Because Yusuf had reconciled his cap table and tidied the data room first, the process runs in weeks rather than dragging on.
Where founders go wrong
Treating Series A diligence like a seed check
— it is deeper and multi-workstream; underpreparing invites price chips.Ignoring open-source licence hygiene
— automated scans surface restrictive licences fast; know what is in your codebase.Leaving IP assignments incomplete
— an unassigned contractor or founder can hold up completion until it is fixed.Not knowing your own model
— inability to defend your assumptions dents investor confidence more than an ambitious number does.
Related questions
How is Series A diligence different from seed?
Seed diligence is a quick look at the cap table, key contracts and IP. Series A is a structured, multi-workstream exercise: legal, financial, commercial and technical teams dig into the company in parallel, and findings feed straight into warranties, price and deal terms. [More: What is due diligence — and what will investors ask for?]
Do VCs really call my customers?
Institutional investors commonly do, with your consent — customer calls test whether the revenue and retention story holds up. Reference calls with management and sometimes ex-colleagues are also common. Line up supportive references early so this stage runs smoothly.
Will investors review my code?
At Series A, often yes. Technical or code review — including automated open-source scans to check licence compliance — is common. If you have used open-source under restrictive licences or have undocumented IP, expect it to surface here.
What is financial-model interrogation?
Investors stress-test the assumptions behind your model: how you built the forecast, unit economics, cohort retention and the sensitivity of the numbers. They are checking the model is defensible, not just optimistic, so know your assumptions cold.
How do I prepare for Series A diligence?
Reconcile your cap table to your filings, paper every share and option grant, complete IP assignments, and tidy your data room before you start. Gaps found in diligence become price chips, warranty demands or escrow holdbacks — better fixed in advance. [More: What legal prep does a startup need before an exit?]
Series A diligence turns every loose thread — an unassigned contractor, a restrictive open-source licence, an unpapered option grant — into a price chip or a warranty. A SuLe solicitor can run a pre-diligence health check so problems get fixed on your timetable, not the investor's. Book a free consultation with a startup solicitor before the fund's lawyers start digging.
Keep reading: How is a Series A different from a seed round legally? · What is due diligence — and what will investors ask for? · What legal prep does a startup need before an exit? · What is a data room and what should be in it? · What are the BVCA model documents? · What is a cap table and how do I keep it clean?
Primary sources: BVCA — British Private Equity & Venture Capital Association · Companies Act 2006
