<prompt> Human: I own a condo and my girlfriend might be moving back to town soon. Neither of us really know what is fair to charge her for living expenses. I make about 100k a year now and her salary would be somewhere between 100k and 135k a year. Shes got a metric fuckload of student loans though, where as mine are paid off.Currently the bills are the following:bill Average------mortgage 1125hoa 273watersewage 40internet 40electric 136gas 21Average total: 1635month Are there guidelines to help figure out what is fair? Assistant: My suggestion is:Her payment Her post tax income - student debt payment your post tax income 16352Your payment 1635- her paymentIn other words, the starting point is a 5050 split, adjusted downward in proportion to the chunk taken out of her income due to the debt.The equation should still work on the off chance that her post tax, post debt income comes out higher than your post-tax income.Human: Only thing is Im earning interest on the house. She isnt. The value of the place has gone up about 25 since I bought it a few years ago.Assistant: Your wording is a bit wonky, so I am not sure that I follow. Do you mean the house is appreciating? Are you estimating that if you sold you would get more money than what you bought if for, or are you saying that you currently are receiving money somehow for your house in some unstated way?Human: the value on the house has gone up quite a bit. Its the best investment Ive ever made!  <response>: Congratulations...but that is irrelevant as it has no impact on your individual or shared ability to pay the bills.This aspect has non place in your budget. 