Who owns how much when we buy together?

The split. Each buyer’s share is what they put in: their part of the down payment, plus the principal repaid by their share of the payments. Interest, property tax and upkeep are treated as the cost of living there, like rent. Many families agree a different split; this gives a fair starting point.

Put it in writing. Decide how title is held (joint tenancy or tenancy in common), who pays what, and what happens if someone wants out, then have a lawyer or notary write a co-ownership agreement. All buyers on the mortgage are fully responsible for it. Check what you can carry with the affordability calculator.