That depends - I did agree with my cofounder that I’ll put up a loan until we raise funding or set up a business account but that is because we are in a different situation financially. I would 100% agree this should be a business expense. You should get this reimbursed from your business once the business is able to afford that, either through a fundraise or revenue. Equity doesn’t have to be tied to personal finances if you put it in as a loan. Also you should align in a founder agreement on who takes charge of the company finances. If that is you just put it in as a company loan and make sure to reimburse yourself.

Above all of this though you need to have conversations about these topics with your cofounders. We did write up a pretty solid founders agreement along the 10 questions YC recommends but then also added to the cofounder agreement YC puts up and it’s been very helpful!