What happens to a co-founder's shares if they leave?
By SuLe · Updated 3 July 2026
By default, nothing happens: shares belong to the person, not the job, so a co-founder who resigns or is dismissed keeps every share they hold. Only contract terms change that — vesting and leaver provisions in your shareholders' agreement or articles, which let unvested shares be bought back at nominal value and set the price for the rest.
Key facts
- Shareholding and employment are legally separate: resigning, or being removed as a director, does not touch a founder's shares.
- With reverse vesting, unvested shares are bought back — or converted to deferred shares — at nominal value when a founder leaves.
- Good leavers typically keep vested shares or sell at market value; bad leavers can be forced to sell at the lower of cost and market value.
- A company buyback must follow Companies Act 2006 Part 18: normally distributable profits or a fresh issue, shareholder approval (the seller cannot vote), and SH03/SH06 filings.
- Transfers to remaining founders attract 0.5% stamp duty only where the price exceeds £1,000 — nominal-value transfers usually fall under it.
Do they really keep everything if we have no agreement?
Yes. Shares are property, and English company law does not confiscate property because its owner stopped turning up. A co-founder who quits in month nine with 40% and no vesting still holds 40% — with the votes, dividend rights and information rights that go with it.
Ending their employment or directorship runs on separate tracks and changes none of that. You are left negotiating to buy the shares back from someone who knows exactly how much leverage they hold.
This is the shares-versus-role separation that catches founders out, and it only cuts one way: the documents you sign in advance are the only tool that reunites the two.
How do vesting and leaver provisions change the outcome?
Vesting splits the departing founder's stake in two. The unvested portion goes back at nominal value — the share's face value, often a fraction of a penny — under the reverse-vesting machinery in the shareholders' agreement or articles.
The vested portion is priced by leaver status. Good leavers — think death, serious illness, dismissal without cause — typically keep vested shares or sell them at market value; bad leavers — early resignation, dismissal for cause — can be forced to sell some or all shares at the lower of cost and market value.
| Situation on departure | Unvested shares | Vested shares |
|---|---|---|
| No agreement, no vesting | None exist — everything is kept | Everything is kept |
| Leaves before the cliff | All recovered at nominal value | None have vested yet |
| Good leaver after the cliff | Recovered at nominal value | Typically kept, or sold at market value |
| Bad leaver | Recovered at nominal value | Can be forced out at the lower of cost and market value |
How does the company actually take the shares back?
Three routes, and the choice matters. A company buyback runs under Companies Act 2006 Part 18: it must normally be funded from distributable profits or a fresh share issue, the shares must be fully paid, payment is due on completion, and shareholders must approve the deal — with the seller barred from voting. Bought-back shares are usually cancelled, with an SH03 (stampable if over £1,000) and SH06 filed.
Early-stage companies often lack distributable profits, so the more common route is a compulsory transfer to the remaining founders or an incoming hire: a stock transfer form and, only where the price exceeds £1,000, stamp duty at 0.5%. Articles can authorise a small cash buyback without distributable profits — capped at the lower of £15,000 or 5% of share capital in a financial year — but tiny startup share capitals make that cap tighter than it sounds.
The third route, where the articles allow it, is converting unvested shares into deferred shares — a class stripped of votes and economic value — which neutralises the stake without anyone funding a purchase.
What if the departing founder is also a director or employee?
Then three separate strands need untangling: the job ends by resignation or dismissal, the directorship by resignation or removal, and the shares move only if your leaver machinery says so. Handling one strand and assuming the others follow is the classic error.
Watch the trigger definitions too. Leaver clauses usually bite on ceasing to be an employee or director — so what counts as "leaving" for a founder who keeps one hat but drops the other should be spelled out, not assumed.
Worked example
Gareth and Lucia run a construction-materials marketplace with 200,000 ordinary shares of £0.01 each — 100,000 apiece — under a shareholders' agreement with 4-year vesting, a 1-year cliff and leaver provisions.
At month 24, Lucia steps back for family reasons and the board agrees she leaves as a good leaver. Half her stake has vested: 50,000 shares, which she keeps. Her 50,000 unvested shares transfer to Gareth at nominal value — £500, with no stamp duty because the price does not exceed £1,000.
The register of members now shows Gareth with 150,000 shares (75%) and Lucia with 50,000 (25%). Without the agreement, Lucia would have kept 50% forever — whoever did the next four years of work.
Where founders go wrong
Assuming resignation brings the shares back.
It does not — without leaver provisions the leaver keeps everything and simply stops contributing.Stopping at director removal.
Taking someone off the board leaves their shareholding, and their votes, completely intact.Planning a buyback the company cannot lawfully fund.
Early startups rarely have distributable profits; check the Part 18 conditions or route the shares to the remaining founders instead.Negotiating leaver terms after someone resigns.
By then every incentive points the wrong way. The terms belong in the shareholders' agreement from day one.
Related questions
Can we just cancel a departing co-founder's shares?
No. Shares cannot simply be deleted because someone left — they must be bought back under the Companies Act 2006 Part 18 rules, transferred under a contractual obligation, or converted into a low-value class if the articles allow it. Each route needs the right paperwork and, usually, prior agreement. [More: Can we buy back shares from a co-founder who has left?]
What can we do if a co-founder has stopped working but keeps their shares?
Without leaver provisions, surprisingly little — the shares are theirs, and heavy-handed tactics can create claims against the company. Realistic options are negotiating a buyout, offering something for the shares, or living with a passive shareholder. It is the exact scenario vesting exists to prevent. [More: What can I do if my co-founder stops working but keeps their shares?]
Does removing a co-founder as a director take away their shares?
No. Directorship and shareholding are separate legal positions: removal from the board ends their management role but leaves every share, vote and dividend right intact. If your leaver provisions are triggered by ceasing to be a director or employee, removal may start that process — check the drafting. [More: How do I remove a co-founder or director legally?]
Who decides whether someone is a good or bad leaver?
Your documents do. Good and bad leaver are contractual labels defined in the shareholders' agreement or articles — the Companies Act does not define them — and the definitions are entirely negotiable. Usually the board applies the definitions to the facts of the departure, which is why precise drafting matters. [More: What are good leaver and bad leaver provisions?]
Leaver situations are where founder goodwill goes to die — and where missing paperwork converts directly into lost equity or litigation. A SuLe solicitor can put vesting and leaver provisions in place before you need them, or steer you through a departure that is already under way. Get your founder documents reviewed — book a free consultation and know exactly where the shares stand.
Keep reading: What is reverse vesting? · What is founder vesting and how does it work in the UK? · What should a shareholders' agreement include for a UK startup? · What is a vesting cliff? · How should co-founders split equity in a UK startup? · Can I fire a co-founder who is also an employee?
Primary sources: Companies Act 2006 · GOV.UK — Running a limited company
