<prompt> Human: EDIT pretty much everyone is focused on the first thing I said, which I had already decided I wasnt going to do. Im going to leave this thread as-is because maybe it will be informative to someone who is considering doing that.backstory:My son is in the process of buying his first house. Hes been saving like crazy for the last few years, and he found a nice little property, for which his savings are just over 20 of the purchase price.However, he did not anticipate the closing costs nor other misc costs like the inspection. The bottom line is, he is going to fall about 9k short of making that 20 down payment.He asked me to borrow that money, because he wants to avoid paying PMI. And I said OK. Then his mortgage officer said that it cannot be a loan; it must be officially declared as a gift. And at first I thought we could say that, but under the table we would have an understanding that it is a loan. But then I got to thinking about why they would stipulate that. And I realized that when he starts making mortgage payments, hes not going to be able to afford to pay back our secret loan.end backstory:Instead of giving him a secret loan, Im wondering about officially putting the money down as a co-buyer. If I did that, I would want to have it arranged in writing that we are not 5050, more like 955 because he will be putting up much more than I will, and also because he will be making the mortgage payments, not me. So do any of you have experience with that kind of arrangement? What kind of financial, legal, and mortgage-application implications would it have for me to be off the mortgage and on the deed with unequal shares?If doing that is legally complicated, or if it would make the bank want to deny his mortgage application, then I wouldnt want to do that. However, the last option would be that he puts down less than 20 and pays PMI until his equity is enough to get rid of that. The cons of which are obvious.So Im looking for advice weighing these three options, or suggestions for other options.  <response>: So Im looking for advice weighing these three options, or suggestions for other options.He could keep saving and then buy a house when he actually has enough money for it. 