You agreed to 50/50 in a bar, or a car, or over Slack with a handshake emoji. Eight months later one of you has shipped every line of code and taken every sales call, and the other has a full-time job and a lot of opinions. Nobody signed anything. Now the resentment has surfaced and there's no document to point at.
This is the most common founder fight there is, and it's fixable. But only if you run the conversation properly, because the way most people open it guarantees a no.
We never signed a cofounder agreement. Can we still change the split?
Yes, and right now is the cheapest it will ever be. If you haven't incorporated, or you've incorporated but haven't issued stock, haven't taken outside money, and haven't signed vesting schedules, the split exists only as a shared belief. Beliefs are editable. Cap tables filed with investors are not, at least not without a conversation involving lawyers and a lot of embarrassment.
The window closes at your first priced round. Once an investor has bought in on the strength of a two-person team split down the middle, reopening it means telling them your founding team is unstable. Do it now, while the only two people who need to agree are in the room.
Worth knowing before you start: Noam Wasserman's research in The Founder's Dilemmas found that 73% of founding teams split the equity within the first month of the venture, usually before anyone knew who would actually do the work. Your handshake wasn't unusually careless. It was normal, and normal is the problem.
How do you open the conversation without it sounding like a power grab?
Don't open with the number. Open with the fact that the agreement was never written down, and ask to fix that. The equity conversation is the second conversation, not the first.
Here's the difference. This is what people say, and it fails:
"I've been doing basically everything for eight months and I think we need to talk about whether 50/50 still makes sense."
Everything after "I've been doing basically everything" is inaudible. You've opened with an accusation and a demand, and your cofounder now has to defend their entire contribution before they can even hear you. They will.
This works better:
"We never actually wrote anything down. No vesting, no roles, nothing on paper. That scares me more than the split does, honestly. Can we spend an hour this week putting an actual agreement together? I'd rather do it while we still like each other."
Two things are true about that opener. It's a request neither of you can reasonably refuse, and it's not a lie. The missing paperwork genuinely is the bigger risk. Say the quiet part too: "I think some of this is going to be uncomfortable and I'd rather have the uncomfortable version than keep being annoyed at you privately."
Schedule it. Not after a bad demo, not at 11pm. An hour, on a calendar, somewhere neither of you can storm out of gracefully.
What your cofounder will say back, and what to say next
They'll push back in one of four ways. Each has a response that keeps the conversation alive instead of ending it.
"I thought we agreed on 50/50. Are you going back on your word?"
"We agreed on 50/50 for a company that didn't exist yet. Neither of us knew what the work would be. I'm not saying you get less because you're worth less. I'm saying we picked a number blind, and now we can see."
"I brought the idea. That's worth something."
It is worth something. It's worth a few points, not half the company.
"It is worth something and I want it counted. What I don't want is it counted at 50% forever. Put a number on the idea, we'll add it in, and then let's count everything else too."
"I have a job. You knew that. I'm doing what I can."
This is the honest one and it deserves an honest answer.
"I did know that, and I'm not angry you have rent. But full-time and part-time can't be worth the same, or full-time makes no sense for anyone. What I want is a way for you to earn back up to 50 when you go full-time. Not a punishment. A schedule."
"Fine, take what you want."
The most dangerous response in the set. Compliance is not agreement, and a cofounder who folds in the room comes back in six months with a lawyer or a slow, quiet withdrawal of effort.
"No, that's worse. If you sign something you think is unfair, you'll hate me for it by spring. Tell me what number you think is right and why. I'd rather argue now."
What the fixed split should actually look like
Stop arguing about percentages and start counting inputs. The two mechanisms that resolve this cleanly are contribution-based recalculation and catch-up vesting, and most teams need a bit of both.
Contribution-based means you list what each of you has put in since the start and value it in dollars, not vibes. Mike Moyer's Slicing Pie model does this formally: unpaid time gets valued at market salary, cash gets counted at face value, and equity tracks the ratio of what each person actually risked. You don't have to adopt the whole system. You do have to do the counting, because "I worked harder" and "you worked harder" is an unwinnable argument, while "I put in 1,400 hours at a $180k market rate and you put in 300 at $150k" is a spreadsheet.
Catch-up vesting fixes the forward-looking half. Say the count lands you at 70/30 today. Instead of freezing that, you agree the part-time founder moves toward 50/50 by hitting specific milestones: going full-time, staying 12 months, closing the first three enterprise contracts. Write the trigger in a form a stranger could verify. "Contributing more" is not a trigger. "Leaves current employer and works 40+ hours/week for six consecutive months" is.
And whatever you land on, put it on paper the same week, with four-year vesting and a one-year cliff on both sides, applied retroactively to your start date so nobody loses credit for the eight months already spent. If sitting down and drafting it together feels like the part you'll both avoid, Servanda gives the conversation a structure and produces a written agreement at the end of it, which is exactly the artifact that was missing when this fight started.
What if they refuse to renegotiate at all?
A flat refusal is information, and it's better than a fake yes. If your cofounder won't count contributions, won't accept vesting, and won't discuss milestones, you've learned that they intend to hold half of everything you build regardless of what they do.
Say it plainly, once:
"If we can't write anything down, I have to decide whether I keep building at this pace for a company where half of it is fixed no matter what happens. I don't want to make that decision. I'd rather we solve this."
Then give it a week. People who dig in during the meeting often come back having done the arithmetic in the shower. If they don't, you're not choosing between conflict and peace. You're choosing between a hard conversation this month and a much harder one in year three, when the numbers are real and the lawyers are billing.
