Legal Question in Real Estate Law in Massachusetts

Re: sharing a house

In general, any agreement concerning land should be in writing. An attorney or accountant can help identify the issues to consider when looking at what should be in such an agreement for sharing a house. One possibility might involve a lease with certain rights in the event she wants out, depending upon how much over fair market rent she is paying. That is, if she is not on the promissory note or mortage, and has not contributed to the down payment, she has no starting equity in the house. If the amount she is willing to pay is not more than fair market rent for the property, should she expect to get "equity" in the property? If she was just an ordinary renter, would she expect to "own" the property after a period of years? So, you might want to look at how much above fair market rent she is paying, and figure out how that compares to the equity you have in the property, and use that to determine whether and if she gets anything if she leaves.

(If you have just made an offer on the property, subject to a financing contingency, can you really afford it if you don't know whether you will have someone to share the expenses? It doesn't sound like it is a done deal with your sister.)