I did this with a recent roommate. I loaned him a couple thousand dollars for furniture and such to get situated in the US, and since I use accounting software

I did this with a recent roommate. I loaned him a couple thousand dollars for furniture and such to get situated in the US, and since I use accounting software to keep track of my finances I find it easier to just issue him an invoice at the end of the month for the remaining debt and any additional transactions that I paid for. If I order food and split it, I charge him 50% on said invoice. Sometimes he tries to say, "Oh, since I got a pizza last week, you can pay for this Chinese food and we're even", and I have to tell them that it's harder to keep a running ledger in my head than to just go through every transaction once at the end of the month and ask, "Is this a 0%, 50%, or 100% expense?" I have him pay via ACH into my dedicated 'incoming personal payments' checking account.