<prompt> Human: Hi rpersonalfinance,My unmarried partner and I are buying a house, and were trying to figure out the best way to handle the money between us. We spoke to a real estate lawyer about putting an agreement in writing yesterday, but now were really skeptical about his advice. So were hoping you can give us some insight.Background: I have a lot of savings, but she does not. We are buying a house for 600K not the real number, but Im simplifying the math with a 20 down payment. She cannot contribute to the down payment, but we can split the closing and recurring costs. We are both on the mortgage and the deed. We also both have very stable income. Goal: Wed like to split the house 5050.Question: How do we set it up so that I pay the entire down payment but we still contribute fairly to the house over the long run?Weve narrowed it down to two options after considering a bunch of options.Option A:I pay the entire down payment. She takes a loan from me for half of it 60K with a normal promissory note at a fair interest rate maybe 6 or so for 10 years. So she would pay me 666 dollars a month on the loan. We just split the house costsliabilities 5050 by putting the same amount each month into a joint bank account and paying the costs from the joint account.Two problems with option A that option B will hopefully avoid: 1 I will have to pay income tax on the interest from the loan. 2 Neither of us will contribute enough to the joint account to claim the entire mortgage interest deduction, so we wont collectively be minimizing our tax burden.So thats why we thought of option B: I pay the entire down payment. Each month for 10 years, she puts into the joint account twice the amount that she would have paid me had I loaned her the money 1332. We then contribute equally to the joint account to cover the rest of the costs of the house. After 10 years, we just cover the costs equally.If we did option B, she would be directly putting more money into the joint account than the annual mortgage interest. So she could take the entire mortgage interest deduction on her taxes. And mathematically, it works out to her paying the same amount as she would have on option A. To see this, just imagine her first giving me 666, then us contributing equally to the account -- its the same as her just paying my first 666 each month. I also wouldnt have to pay income taxes on the extra amount she contributes to the house since it isnt income to me -- its a contribution to our joint account thats used for housing costs -- I gain equity via her payments, but its unrealized until the sale of the house.The main problems we see with option B involve how to spell out exit conditions on the agreement like what happens if we sell the house, one of us dies, etc. As far as I can tell though, there is no inherent problem with spelling those out -- its just more complicated mathematically.Our lawyer insisted that we should go with option A, but only because B was too complicated. She and I both have PhDs in math-related fields, so were not too worried about that, frankly. Am I right in thinking that option B is actually much better for us financially?Thanks for any thoughts you have! This is in Pennsylvania, in case that matters. Also, I know youre not my lawyer which might be the problem in the first place ....  <response>: Damn 6 interest to your prospective future wife... Yeah probably not prospective future wife. 