<prompt> Human: Here is my current situation rounded numbers:2-unit house, with 2100month mortgagetaxesinsuranceRenting out one unit for 2100month under market rent Renting out one room for 700 and split utilities in unit I live in also under market rent, so total 2.8kmonth in rental income.My 9-5 regular job 100k, my girlfriend 50k. She currently pays 850month for her apartment sharing with her girl friend in pretty bad shape place since it has not been renovated in a long time compared to mine. I would need to get rid off my roommate with 700month rent for my girlfriend to move in.What do you think is fair share she should be contributing? --- Update 2 ---1. I live in a state which does not recognize common law status. Thanks for bringing this up though in case it would help someone else. 2. Weve been together under 10 months.---UPDATE 1---Wow, I was not expecting so many replies! Thank you everyone. Few pointsresponses to common comments below:1. Idea of her paying for any repairs in the house has not even crossed my mind. I would be responsible for it all as Im now 100.2. I will have a rental contract in place with her, month to month, as I have now with current tenantroommate. 3. Market rate for room is 900, hence I mentioned current rent is under market as is.4. Current roommate cannot stay because 1. She would take over the room We are fairly introverted so we need our own spaces 2. We need privacy, 3. Three people would be too much5. Folks who mention that Im breaking even so I should not charge her are incorrect-- taxes water cost alone take a cut. Upcoming and ongoing outside repairsrenovations are needed as well. Hence having current roommate.Assistant: Why do you need to get rid of your roommate? Human: To echo, Spurty, it is more about comfort-ability and privacy. Plus, the currently occupied room by my roommate would be solely my girlfriends.  <response>: If she gets her own room, I think 700 is fair. 