Research on thousands of startups by Harvard Business School's Noam Wasserman found that about 65 percent of high-potential startups fail because of tension between founders — more than lose to competition. A cofounder agreement is the document that settles equity, decisions, work and exits before those tensions meet money, and the best time to write it is while the founders still agree.
Heroines publishes information, not legal advice. Agreement drafting belongs with a startup lawyer; this guide covers the terms founders should walk in knowing.
Which terms matter most in a cofounder agreement?
Four sections do most of the work, and every one is cheaper to negotiate on day one than in a dispute.
- Equity split and why: the percentage each founder holds and the stated logic — contribution, capital, time — so the reasoning survives the memory.
- Vesting: equity earned over time, commonly four years with a one-year cliff, so a founder who exits early does not leave with a permanent stake.
- Roles and decisions: who owns which function, and which choices — spending above a threshold, hiring, borrowing — need agreement versus one founder's call.
- Exit and deadlock: what happens if a founder wants out, stops working, or the pair cannot agree — buyback formulas, valuation method, tie-breaker.
How should two founders split the equity?
However they decide — and on the record. Equal splits are common and defensible when contributions are genuinely symmetric. When they are not, founders who fund the company, work full-time while a counterpart stays employed elsewhere, or contribute intellectual property often take a larger share. The dangerous split is not the unequal one; it is the unspoken one.
Wasserman's same research found founders who avoided the hard conversation for the sake of harmony paid for it later. Writing down the rationale, even for a 50-50 split, turns a future argument into a reference document.
What does vesting actually protect against?
Vesting protects the company from a departing founder keeping a large stake while everyone remaining carries the work. Under a standard four-year schedule with a one-year cliff, a cofounder who leaves in month ten takes nothing earned; one who stays four years keeps the full grant. Investors expect it, and its absence is a common red flag in diligence.
For women founders pairing with a technical or industry counterpart, vesting also equalizes risk honestly: the partner keeping a salary elsewhere can vest on the same clock as the founder who quit her job, and the agreement can say so.
Related stories: Should a woman founder bootstrap or raise venture money? · Which small business grants can women owners actually win?.
What should the agreement say about money?
Money changes the temperature, so the document should anticipate it: how much each founder may invest, whether early personal investment converts to equity or a loan, what happens to equity if the company raises a priced round, and who may sign the company into debt. The SBA's business guide covers the ownership-structure basics founders should settle with counsel before these clauses are drafted.
| Trigger | Question the clause answers |
|---|---|
| A founder quits | Does unvested equity return to the company? At what price? |
| A founder underperforms | Is there a reduction-for-cause mechanism? |
| Deadlock | Who breaks the tie, or does the company split or sell? |
| Outside offer for the company | Can one founder block a sale the other wants? |
How do founders talk about this without souring the partnership?
Three practices help. Draft in a working session with a lawyer, so the hard items are on a neutral agenda rather than one founder's list. Use scenarios instead of accusations — "what if one of us wants out in year two" — which keeps the conversation about the future, not suspicions. And revisit the agreement at funding events, when reality tests every assumption.
The document is not a bet against the partnership. It is the reason a disagreement, when it comes, has somewhere to go.
What does a minimal version look like?
A workable starter covers five items on two pages: the equity split and rationale; a four-year vesting schedule with a one-year cliff; named roles; a decision threshold requiring both signatures; and a buy-sell clause for exits and deadlock. Anything is better than nothing, and nothing is what most founding pairs have when the first fight arrives.
What happens when a founding pair skips the agreement?
The default outcomes are worse than most founders imagine. Without a written split, state partnership law can impose a 50-50 arrangement nobody intended, and unwinding it means negotiation at the worst possible moment — when trust is already spent. Without vesting, a cofounder who departs in month four may keep a full quarter of the company, sitting on the cap table while the remaining founder works and future investors deduct the dead equity from their offers.
The remedy is usually expensive: a buyout negotiated under pressure, mediation fees, or litigation that consumes the runway the product needed. Startup lawyers describe these matters as among the most predictable and most avoidable disputes they handle, which is the quiet argument for the two-page document: the cheapest version of the conversation is the one had early, in writing, while goodwill is still the founding pair's largest asset.