<prompt> Human: My wife and i recently decided that we wanted to be closer to family so we talked to her father and are going to buy a duplex. Most of the up front money will be coming from him and his wife with them being on the deed for the house and us technically renting one of the duplexes out. It was never verbally agreed upon or put in writing that things would be split 5050 when we do actually go through with buying the duplex so thats where things might get fuzzy. In our searching we found one that we all liked and have put an offer on. Nothing has been accepted yet but we are figuring out our financials for monthly costs. He is the only one that has seen a breakdown of the utilities on paper and says that it would be about 328 a month for utilities. The purchase price of the duplex is 239900 and we are putting 20 down. He says that because it is not homesteaded he will be paying a higher rate of 4.7 over the 4.0 that he would get otherwise. We have also looked at property taxes for the past few years and they have hovered around 4,300.With all of this information I am getting a monthly cost of running the house at around 1750 a month, also factoring in 840 a year for homeowners insurance with a calculator that I had gotten set up on excel sheet. This next part is what makes me think that hes wanting to profit off of us. He had said that his estimation of the monthly housing costs would be 2100 a month and that my wife and I would be paying 1100 a month plus utilities. We are also renting the much smaller property that is a 2 bed 1 bath, theirs is a 3 bed 2 bath.tl;dr I estimate shared housing to be 1750 and father-in-law says 2100My question is are there any extra costs that Im not factoring in here?  <response>: Do not put a down payment on a home you dont own. If your FIL wants to buy a home and charge you rent thats one thing, but if he is charging you rent and having you contribute a down payment or pay for maintenance improvements that isnt something you want to be a part of. 