Most cofounder breakups are not caused by the idea. They are caused by things nobody said out loud at the start. Noam Wasserman's research on thousands of startups points the same direction: the people problems sink more companies than the product problems do. The questions to ask a potential cofounder are the ones that surface those assumptions while walking away is still cheap.
This is not an interview. The goal is not a yes or a no. It is a real conversation that shows you how someone thinks about money, power, and pressure before any of it is on the line. Answer these independently, then compare. Where you disagree is not a failure. It is information you would rather have now than in month eighteen.
Here are twenty questions, grouped into the six themes that decide whether a partnership holds.
Values and motivation
Start here, because everything else inherits from it. Two people can agree on the idea and still want completely different lives from it.
- Why this problem, and why now? Listen for a reason that survives a hard year, not a passing interest.
- What does success look like for you in five years — the number, and the life around it?
- Would you rather own a smaller slice of something huge or a large slice of something solid?
- What would make you walk away, even if the company were doing fine?
If one of you is building a lifestyle business and the other is building a rocket, no equity split fixes that. Name it now.
Money and equity
The most avoided conversation, and the one that curdles fastest when skipped. First Round's cofounder questionnaire treats equity as a natural friction point for a reason — it is really a conversation about power and trust.
- How much do you need to earn to keep going, and for how long can you go without it?
- How should we split equity, and what does that split reward — past work, future risk, or role?
- How do we handle it if one of us contributes far more, or far less, than we planned?
Get to a real number, not a shrug. Someone who cannot tell you their runway cannot commit to a runway, and someone who bristles at the equity question now will bristle harder when there is something to divide. Equal splits feel fair and often are, but decide it on purpose rather than by default. When you are ready to formalize the split and vesting, our cofounder agreement checklist walks through what belongs in writing.
Roles and authority
Ambiguity here feels collaborative early and turns corrosive later. You do not need rigid job descriptions on day one. You do need to know who decides what.
- Who is CEO, and what does that title actually mean in how we work?
- When we deadlock on something important, who breaks the tie — and in which domains?
- What are you clearly better at than me, and where do you want me to lead without checking in?
Naming a tiebreaker is not a power grab. It is how you avoid the slow paralysis of two equal votes and no mechanism. If you want a structured way to divide ownership of decisions, see cofounder roles and responsibilities.
Working style
You will spend more waking hours with this person than with almost anyone else. Style differences are survivable, but only if they are visible.
- How do you prefer to make decisions — fast and reversible, or slow and thorough?
- What does a normal week look like for you, and what pace can you actually sustain?
- How do you like to receive hard feedback, and how do you tend to give it?
There is no correct answer. A methodical builder and a fast mover can be a strong pair. Two people who each assumed the other worked their way is where resentment grows.
Commitment and runway
Intentions are cheap in a coffee shop. This theme tests whether the intention has a shape.
- Is this full-time for you, and if not, when does it become full-time?
- What personal circumstances — family, finances, health, other ventures — could pull your focus in the next two years?
- If we raised nothing for eighteen months, would you still be here?
Ask plainly, and give an honest answer yourself. A cofounder with a young family and a mortgage is not a worse cofounder. But you both need to plan around the real picture, not the flattering one.
Conflict and exit
The hardest theme, and the clearest signal. How someone talks about ending things tells you how they will behave during them.
- When we disagree and both feel strongly, how do you want to work through it?
- Tell me about a serious conflict with a past partner or teammate — what happened, and what was your part in it?
- If one of us needed to leave, what would a fair exit look like?
- What would you want to be true about how we treated each other, even if this doesn't work?
Watch for someone who blames every past cofounder entirely, or who refuses to discuss exit as if naming it invites failure. The opposite is the good sign: a person who can sit inside an uncomfortable question calmly is a person you can fight with and stay partners. If conflict is already where your worry sits, our guide to cofounder conflict covers how healthy partnerships handle it.
Turning answers into alignment
Twenty questions will not give you certainty. They will give you a map of where you already agree, where you differ, and where one of you has never thought it through. That map is the point.
Do three things with it. Write your answers down separately before you compare, so you are not just nodding along to the answer you hoped to hear. Do the work of a small real project together, because behavior under a deadline tells you more than any answer given in a calm room. And call two or three people who have built something with your potential cofounder. References catch the patterns a warm conversation is designed to hide, and the way someone speaks about former partners is a preview of how they will one day speak about you.
You do not need to agree on all twenty. Aim instead for a short list of true non-negotiables — two or three things where a mismatch really would end it — and hold the rest loosely. Most differences are workable once they are named.
If you want a structured starting point, our cofounder alignment check turns these themes into a shared exercise you both complete, and our cofounder compatibility guide covers the traits that matter beyond a single conversation.
The founders who last are rarely the ones who agreed on everything. They are the ones who found the disagreements early, said them out loud, and decided together what to do. Start there.
Frequently asked questions
- What should you ask a potential cofounder?
- Ask about the things that quietly break partnerships: why they want to build this, how much money they need to live on, who holds final say in a deadlock, and how they behave under stress. The point is not to collect right answers. It is to hear how someone thinks when the stakes are real.
- How do you vet a cofounder?
- Work together before you commit. Run a small project, sit through a hard decision, and watch how they handle disagreement and follow-through. Then have the money, equity, and exit conversations explicitly, and call two or three people who have worked with them. Reference checks catch patterns a good interview hides.
- What are red flags in a potential cofounder?
- Vague answers on money and commitment, an unwillingness to discuss equity or exit, blaming past cofounders entirely, and treating every question as a test to pass rather than a conversation to have. Someone who cannot disagree with you calmly now will not learn to under pressure.
- When should you have these conversations?
- Before you sign anything and ideally before you write real code together. The best window is after you know each other and share an idea you both want to pursue, but while walking away is still cheap. Waiting until incorporation makes every honest answer feel like a renegotiation.
- Should you put the answers in writing?
- Yes. Answer independently, then compare. Writing forces specificity that conversation lets you skip, and a shared document becomes the reference you return to when memories diverge a year in. It also feeds directly into your founder agreement and equity split.
