<prompt> Human: My fiancé and I are about to buy a house. Weve found something we love, and can afford, and using some calculators from rpersonalfinance we believe our break even point compared to renting to be around 6 years, and we plan to stay there for at least 8 years. We will be paying 20k per year in property taxes and interest for the first few years, and I was excited that this was all deductible. At a 28 tax bracket, that would effectively be about 450 per month coming back to us. After everything is factored in extra utilities, HOA, insurance, etc, this would make our total housing cost about the same as our current rent, which makes everything simple. Or so I stupidly thought.But as first time home buyers, I didnt realize that these must be itemized, meaning we have to lose our standard deductions. Thats annoying, but its ok. If we get married and file jointly, the amount deducted 20k is still more than married standard deduction 12k, so the extra bonus from taxes is only the 8k difference or about 180 per month. If we get married and file separately, the IRS says that we effectively have to both itemize our deductions, or both take the standard deduction. So the bonus numbers come out the same 180 per month. But what if we dont get married?As I understand it, 2 non-married people in a joint mortgage can split up their deductions proportionally. For my fiancé and I, we could decide that I pay the mortgage and property taxes, and she pays the other expenses. Then she should be able to keep her standard deduction, while I itemize. There is no tax law I can find that says we must both do one or the other. A single standard deduction is 6k, which changes the effective bonus from our existing taxes to be 28 of 14k 20k - 6k. That comes out to about 325 per month.Is it really almost 150month cheaper for us to remain single? Or is there some obvious or not so obvious flaw in my understanding? Additional infoNeither of us are likely to have any other significant source for itemizing deductions that I have discovered. We make a combined total of 180kyear, with steady employment. Our Mortgage-to-gross income ratio is 2.2.tl;dr I think that its 150month cheaper to be single than married, because IRS will force us to go all-in on itemizing or taking the standard deductions. They dont force us if were just friends.update: Thanks guys! uwisnowbird pointed out that I had forgotten to include the state income taxes in my itemized deductions. This brings the difference between married and single to about 42 dollars per month, which is within my margin of error for the rest of the calculations. This is pretty reassuring.  <response>: But as first time home buyers, I didnt realize that these must be itemized, meaning we have to lose our standard deductions. Ill take Things I wish realtorsmortgage brokers were required to tell first time buyers for 200, Alex.So many people look at home buying and think, Cha-ching! Tax deductions! And then they find this out, which means they dont understand how tax deductions work. The standard deduction is not free money the government gives you. Its a generic estimate of the amount of tax deductible stuff you do in a year that the government is willing to stipulate to without documentation. If you want to deduct more than that, you have to itemize aka, you have to prove why you get to deduct more than that. But that obviously means your itemized deductions are instead of the standard deduction, because youre telling the IRS, Thanks for the vote of confidence that Id have 12k of deductible activity this year, but I actually have 20k and heres my proof.As for whether youre better off filing single or married or married filing jointly, do a sample return for each scenario and see what happens.Edit: Also, there are benefits to getting married beyond taxation. For example, legal next of kin status. I wouldnt hinge a marriage decision based on whether or not youll pay a couple hundred more in taxes. 