Have they changed in MD? I was under the understanding that in MD, you paid a stiff one time tax when you purchased/registered the boat, but annually thereafter, there was no property tax on boats in MD. In NC, you pay a relatively small tax when you purchase the boat and then a property tax every year at the same rate assessed against cars or houses. The marinas are required to submit to the tax office a listing of boats in the marina on January 1...that's how they know about you, and as others have said, they will expect tax to be paid. I have a couple of boats registered in NC that I keep in the adjoining county (where I pay the property tax on these items), but the local county doesn't know this and I get nasty notes from them every year saying they found that I haven't paid taxes on these NC registered boats...of course a note saying where I pay the taxes takes care of the situation after they check it out.