<prompt> Human: My father is self employed. Very good credit and revenue stream but usually claims a loss. He wants to sell the house he is currently in and buy another house. His current house is 340k and he owes 80k on it. He will put 50 down payment for the new house he is looking at which is going for 720k. My father is asking me if I could co-sign since I get W2 and Im not self-employed. Hence, it will be easier for him to get the mortgage.I have excellent credit 791 and I have my own mortgage. Should I do this favor? I know it will technically increase my debt and it will impact me if I ever wanted to sell my house and buy something else. Though, Im pretty sure I want to stay in my house for the long haul. Thoughts?Thank you everyone. I was leaning towards not co-signing but this has definitely confirmed it.  <response>: My father is self employed. Very good credit and revenue stream but usually claims a loss.This is kind of a red flag to me. Banks lend to self-employed people all the time - there shouldnt be a problem showing them proof of income. You may know more about his circumstances, but heres some options I see: Your father doesnt actually make much money and needs a cosigner. Claiming a loss at best means that his business is not profitable. In this case, I dont think its wise to get financially tethered to this house. Your father is hiding his income from the IRS the worse option for claiming a loss and doesnt want to share some information with the bank. If this is the case, then you are one audit away from being fully responsible for paying the mortgage. Certainly not accusing here, but it did come to mind when you say good revenue and claiming a loss . He hasnt actually tried to get the mortgage yet so he doesnt realize that his self-employment income will be sufficient. This is the most favorable outcome.One way or another, its almost never a good idea to cosign for something, and a house is a huge deal. I think you have an idea of what youre getting into, but I would definitely press hard to see why the bank wont give your father a loan by himself. 