The first thing to do is to get out your deed and see what it says. Then, if you have a mortgage, usually the mortgage company insists on a site survey to show boundaries and the location of the home on the property. This also should be with your purchase papers. Were you represented by an attorney when you made the purchase? If you were, I would consult with him before going any further. No need to go to the town hall, because this is a civil matter and they won't get involved. All you will do it bring the problem to the surface and it might get any future building permits denied, until the problem is resolved. When you purchased the home, did you purchase title insurance? If you did, then the title company will also have a stake in making sure that what you purchased is what you got. One problem that does arise often, is the real estate broker says the line goes to point X, as represented by the seller. Problem is that neither the seller or the agent really know if this is true. If you were not represented by an attorney, don't have title insurance, and the property has never been surveyed specifically for you, then save you money and go directly to a licensed surveyor with your deed and get the property surveyed. Once you pay for the survey, and are satisfied that the lines are correct, then we can discuss the problem further. Until then, you are just guessing. If this rear property line effects your neighbors also, possibly you might get the neighbor on the right and left to also have there property surveyed by the same person that you use. This will help to keep the cost down for everyone. Also, once you have the survey in hand, take a copy with the raised seal to the town or county where deeds are registered, and have the survey filed. It cost about $10 usually to file a survey, and this puts all adjoining properer owners on record that what the survey claims is yours, you claim as yours. If it varies from the original deed description, then you are going to need an attorney to join in to help resolve the issue. Just keep your cool and remember, that this isn't going to be resolved for possibly 6 months to a year. No matter what, in the end, you will need a legal survey, so you might as well start there and not waste money in any other direction until you know all the facts. I just hope that you don't have a deed that reads "from the big oak tree, to the stone pile, to the snow pile, and back to the beginning." Those type of deeds are the ones that cause the most problems. Since you said that it is part of a Sub Division, this should make it easier to establish the boundaries. Where the street is, can't be changed, but the rear lot line is the important issue here.