[gojomo]

Only you two can negotiate that. Your "top accelerator" also may be able to help with advice.

How much does the prior tech guy retain?

That there's been some de-risking may be relevant... but the past is still fixed/sunk-costs, while the future is open-ended. Treating this, new partnership/new-accelerator, as a re-founding might be fairest, if new guy is the right choice for the long haul. And he might have another equally-good option where he can be a full equal partner. So your project seniority and full-time-work-so-far may not be dispositive.

50/50 can risk deadlock without a 'shotgun clause' or other tiebreaker, in situations where the working relationship collapses but there's still value to fight over.

"won't be taking salary but a loan" seems weird. If the company craters, who will he be paying the loan back to? Cash removed from working accounts to pay a team member's living expenses, cash that could be useful today, is just as dear as paying a salary would be.

[samnadine]

the prior guy has no shares anymore.

These sunk-costs (traction, incubation, awards..) have been the reasons why we've been selected. Joining after is lowering the risk. If he would have started long time ago then 50/50, like with the prior guy.

The loan is a personal loan from the first incubator, which hasn't to be fully pay back in case you fail.

[gojomo]

(1) risks lawsuit unless there's an ironclad purchase/assignment-of-rights with prior guy

(2) only you and he can weigh that prior progress against his future value, and each of your next-best-options.

(3) still fishy and seems irrelevant; if he's receiving cash-up-front from business for living expenses, that either -- (a) won't be paid back in fail-scenario, or (b) will be paid back, when there's plenty of money and it doesn't matter, in succeed-scenario -- then it's mostly like salary, and there shouldn't be brownie points for calling it a 'loan'.

[dylanhassinger]

how long does new guy intend to be around?

How much effort is gonna put in? 40 hours/week or 100?

those would be my questions. No matter what, use a vesting schedule (so you're covered in case he isn't the right cto).

What if it was 5% vested every 6 months, up to a total of 49%?

[samnadine]

Full commitment, shares vested over 4 years with one year cliff.

how do you write on paper/agreement you need to commit more than a full job, like 60h/w?

[gojomo]

Trying to put a "60h/week" commitment into a contract is unwise on many levels:

It's trying to measure by clock-watching something inherently qualitative rather than quantitative.

Most people can't be productive and efficient with that kind of sustained time-on-task, for more than brief crunch periods.

And, if they're a co-founder, you need to trust them, and be setting mutual understandings, at a much deeper level than some contract.

Your jurisdiction's law may (and probably does) differ from the US, but if there's some process by which he (or conversely you) can be let go if things aren't working out, and thus any payments or vesting stops, then that's your elastic all-purposes way to deal with someone's failure to meet expectations. Writing down some unrealistic commitment metrics can't replace the kind of deep mutual trust and shared mission you'll need.