A startup cofounder agreement is a written contract between founders that sets out who owns what, what each person commits, and what happens if someone leaves. Founders should sign one early -- before building or raising -- because it prevents the ownership and commitment disputes that sink more startups than bad products do. It is the founder-to-founder layer that sits beneath incorporation.
This post covers what a cofounder agreement actually contains, how to think about equity splits and vesting, and how the agreement relates to forming your legal entity. It is practical guidance for early-stage founders, not legal advice -- loop in a lawyer before you sign.
TL;DR
- Sign before you build: a cofounder agreement is cheapest and easiest when there is nothing to fight over yet.
- Cover the basics: equity split, vesting, roles, IP assignment, leave terms, and dispute resolution.
- Vesting protects the company: a 4-year schedule with a 1-year cliff keeps equity tied to continued contribution.
- It is not incorporation: the agreement is founder-to-founder; incorporation creates the legal entity that issues the shares.
- Use a lawyer: templates help you think, but a real agreement should be reviewed before signing.
What Is a Cofounder Agreement?
A cofounder agreement is a contract among the people starting a company. It records the deal they are making with each other: how ownership is divided, what each founder is responsible for, how much time they are committing, who owns the intellectual property, and what happens if the relationship breaks down.
It is distinct from the paperwork that creates your company. When you form a corporation or LLC, the entity issues shares to founders. The cofounder agreement is the private understanding that explains why the shares are split the way they are and what each founder must do to keep them. You can sign a cofounder agreement before you incorporate, and many founders do, because the conversation is the valuable part.
Think of it as the prenuptial agreement for your startup. Nobody enjoys writing one, but the cost of not having it is paid later, in legal fees and lost equity, when emotions and stakes are high. If you are still figuring out who to build with, this guide on finding a cofounder is the right place to start before you draft terms.
What Does a Cofounder Agreement Cover?
A complete agreement typically addresses six areas. Skipping any one of them is the source of most founder disputes.
- Equity split and ownership -- the percentage each founder holds and the class of equity.
- Vesting schedule -- how and when that equity is earned over time.
- Roles and time commitments -- who does what and how many hours per week.
- IP assignment -- that all work product belongs to the company, not the individual.
- Departure terms -- what happens to equity if a founder leaves, including bad-leaver and good-leaver distinctions.
- Dispute resolution -- how deadlocks and disagreements are broken.
None of these are exotic. They are the questions every founding team answers informally in the first week and then forgets to write down. The agreement is just making that informal deal enforceable and explicit.
How Should Cofounders Split Equity?
The two common approaches are an equal split and a role-based split. Neither is automatically right; the right answer depends on contribution, risk, and who is full-time versus part-time.
| Approach | When it fits | Risk to watch |
|---|---|---|
| Equal split (50/50, 33/33/33) | Co-founders with identical commitment, risk, and skills | Resentment if one person carries the load |
| Role-based split | Uneven contributions, e.g. one full-time, one advisor-level | Hard to quantify "who is more essential" |
| Split with a founder vesting backstop | Any team, to protect against early departures | Needs clear vesting terms agreed up front |
A useful rule of thumb: split equity based on the future value each founder is committing to create, not just the ideas they walked in with. The person writing the first line of code and the person who conceived the idea are both founders, but their ongoing commitment may differ. Vesting, covered next, is how you make an unequal or equal split safe.
If you are also setting up your books alongside the agreement, these startup accounting basics will help you track cap table changes cleanly from day one.
What Is Cofounder Vesting and Why Does It Matter?
Vesting means a founder earns their equity over time rather than owning it all on day one. The standard startup schedule is four years with a one-year cliff. "Four years" means equity is earned monthly across 48 months. "One-year cliff" means if a founder leaves before 12 months, they forfeit all unvested equity.
Vesting matters because it answers a brutal question: what if a cofounder quits after three months but keeps 50% of the company? Without vesting, that scenario is real and common. With a cliff, the company can continue without a ghost shareholder blocking decisions or claiming upside they did not earn.
Vesting is not a vote of distrust. It is the default expectation for any venture-backed company, and investors will ask about it. Agreeing to it early signals to future investors that the team is serious and the cap table is clean.
How Are Roles and Time Commitments Defined?
The agreement should state each founder's area of responsibility and the time they are committing. "CEO and product" or "CTO and engineering" is enough at the title level, but the time commitment is what matters most: is this founder full-time, or are they keeping a day job?
Putting time commitments in writing prevents the silent drift where one founder assumes the other is all-in while the other is moonlighting. It also feeds into the departure terms: a founder who promised full-time but delivers ten hours a week is a different problem than one who gave notice and left cleanly.
Keep this section practical. A sentence per founder about scope and a line about full-time versus part-time is sufficient. The goal is alignment, not a job description.
Who Owns the IP in a Cofounder Agreement?
Every founder should assign the intellectual property they create to the company. This includes code, designs, trademarks, and written material produced for the business. Without a clear IP assignment, a departing founder could argue they personally own the prototype they built on nights and weekends.
This clause is especially important before incorporation, when there is no legal entity yet to hold the IP. The agreement should state that all pre-incorporation work is assigned to the company upon its formation. It is one of the clauses you most want a lawyer to review, because IP ownership mistakes are expensive to unwind later.
What Happens If a Cofounder Leaves?
This is the clause founders most regret skipping. The agreement should define what equity a departing founder keeps and what is forfeited, using bad-leaver and good-leaver categories.
- Good leaver: leaves for acceptable reasons -- illness, death, mutual agreement, or being terminated without cause. Typically keeps vested equity.
- Bad leaver: leaves by walking away, breaches the agreement, or is fired for cause. Often forfeits unvested equity and may face repurchase of vested shares at a low price.
A repurchase right lets the company buy back a departing founder's shares, often at the lower of fair market value or original cost for bad leavers. This keeps equity available to redistribute to a replacement or to the remaining founders.
The point is not to punish anyone. It is to make sure the people building the company today are the ones who own it tomorrow.
How Does a Cofounder Agreement Relate to Incorporation?
The cofounder agreement is the founder-to-founder deal; incorporation is the legal act of creating the entity that issues the equity. They work together but are not the same document.
You can sign the cofounder agreement first, even before there is a company, to lock in the understanding. Then, at incorporation, the company issues shares per the agreed split and the vesting schedule is reflected in the stock purchase or restricted stock documents. The agreement points forward to those documents; it does not replace them.
If you raise outside capital, your investors will expect both: a clean cap table from proper incorporation and evidence that founder equity is vested and IP is assigned. Doing the cofounder agreement well makes the financing paperwork straightforward.
When Should Founders Sign a Cofounder Agreement?
As early as possible -- ideally before any meaningful work, code, or fundraising begins. The agreement is easiest to negotiate when there is nothing to divide and everyone is optimistic. Waiting until there is money or traction on the table turns a friendly conversation into a high-stakes negotiation.
If you have already started building, sign now rather than waiting for the "right moment." The right moment rarely arrives, and the cost of ambiguity grows with every commit, customer, and dollar. Pair it with your incorporation step so the two are consistent from the start.
And remember the disclaimer that applies to everything above: this is general founder education, not legal advice. Founders should use a qualified lawyer to draft or review their actual agreement. The goal of this post is to help you know what to ask for and why.
FAQ
Q: Do Cofounders Legally Need a Written Agreement?
A: No jurisdiction requires cofounders to have a written agreement, but operating without one is risky. If founders disagree on ownership or contributions and there is nothing in writing, courts may infer terms from conduct, which is unpredictable and expensive to resolve. A written cofounder agreement makes each founder's rights and obligations explicit and is expected by investors.
Q: What Is a Standard Cofounder Vesting Schedule?
A: The standard schedule is four years with a one-year cliff. Equity vests monthly over 48 months, and if a founder leaves before 12 months they forfeit all unvested shares. After the cliff, a departing founder keeps the portion that has vested. This structure keeps equity tied to continued contribution and is the default expectation for venture-backed startups.
Q: What Is a Bad-Leaver Clause in a Cofounder Agreement?
A: A bad-leaver clause defines circumstances -- such as walking away, breaching the agreement, or being fired for cause -- under which a departing founder forfeits unvested equity and may be required to sell vested shares back to the company at a low price. It is paired with a good-leaver clause for acceptable departures, and it protects the company from a founder who leaves early yet keeps a large ownership stake.
Q: Is a Cofounder Agreement the Same as Incorporation?
A: No. A cofounder agreement is the private contract between founders setting out equity, roles, vesting, and IP. Incorporation is the legal process of forming a company that issues the equity. The agreement can be signed before incorporation and points forward to the formation documents; it does not create the entity or replace the corporate paperwork.