the estimation for registering a trailer and a boat are different. You can't use the online service to estimate them. You can get info for registering one or the other.
there is more about  sales tax payment or sales tax exemption, or purchase price. Should I accept the invoice?
Bring your dealer's bill of sale showing that you paid New York State sales tax. Also bring a bill of sale from the MV-50 NY State dealer only or a complete sales tax exemption {Sales Tax Form} pdf at the New York State Department of Taxation and Finance DTF-803 for a departure from - state dealer.
Got it. Another question that I have about trailers and boats registration, what proof do i need?