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splitting a joint mortgage - one owner in home
Get a lawyer to put this in contract form, with everything spelled out explicitly. What is fair is what the two of you agree upon. My own suggestion: Divide the property into things which are yours, his, and shared, then have each of you be responsible for all your costs plus half the shared costs, but get all the benefits of your half. That would mean that if he rents out his half, all the rental income is his; if you decide to live in your half, all the savings of not paying rent are yours.  Each of you pays your half of mortgage, insurance, and other shared costs. Repairs to shared infrastructure should be done by someone both of you trust. If you agree the work is needed and he does it rather than your hiring someone, you owe him the appropriate percentage of the costs; the two of you will need to agree on whether you owe him for that percentage of his time as well. Make sure you agree on some mechanism for one person offering to buy the other out, or to sell their half to the other party... or potentially to someone else entirely. (Personally, I would try to do that at soonest opportunity, to avoid some of the ways this can go wrong -- see past comments about the hazards of guaranteeing a loan; this works or doesn't work similarly.) Does that address your question?