Share your insights or perspective on the financial matter presented in the input.

In a house with shared ownership, if one person moves out and the other assumes mortgage, how do we determine who owns what share in the end?
I second (or fifth?) the answers of the other users in that this should have been foreseen and discussed prior to entering the partnership.  But to offer a potential solution: If the mortgage company allows you to assume the whole mortgage (big if) you could buy the other partner out. To determine what a fair buyout would be, take the current value of the house less the remaining mortgage to get the current equity. Half that is each partner's current gain (or potentially loss), and could be considered a fair buyout. At this point the partner realizes any gains made in the last 5 years, and from now on the whole house (and any future gains or losses) will be yours. Alternatively your partner could remain a full partner (if s/he so desires) until the house sells. You would see the house as a separate business, split the cost as you have, and you would pay fair market rent each month (half of which would come back to you). A third option would be to refinance the house, with you as a sole mortgage holder. To factor in how much your partner should receive out of the transaction, you can take his/her current equity and subtract half of the costs associated with the refi. I would also recommend both of you seek out the help of a real estate lawyer at this point to help you draft an agreement. It sounds like you're still on good terms, so you could see a lawyer together; this would be helpful because they should know all the things you should look out for in a situation like this. Good luck!