A survey would answer your a boundary dispute (could cost $500-$1000). If the survey revealed that your neighbor encroached on your property, then I would try to talk it out with them and if you can't get it resolved, you'll need to contact an attorney. You should disclose this possible problem with any buyers who write an offer on your home. Disclose, disclose, disclose.

Hi Jennifer,

You need to have a survey if you haven't had one done already. In Hawaii, a survey is required for all homes that involve a lot purchase at the same time, for this very reason. At closing, if there are any encroachments (such a fence) on your property, they are only allowed to extend a very short distance (1/2 a foot or so) on to your property.
Since you will probably need a survey anyway, I would start shopping for a surveyor now. You will need to get that fence issue cleared up anyway, so it doesn't come back to cause problems later.

First I would ask if your home is listed with a Realtor. If it is, you might have your Realtor check the plat and measure your property. That would tell if the fence is on your property or not and perhaps by how much if it is on your property. IF it is on your property, I would contact the neighbor and try to settle the dispute using the plat and lot dimensions. If the neighbor is not obliging, then you could have a surveyer to survey the property and follow up per what the surveyer determines. If the fence is on your property, the neighbor is obligated to remove it, however, he/she may put up some resistance. Hopefully you know the neighbor and can settle this without difficulty.