Go to the county tax office and let them know the date you are leaving. There is no partial refund for the Personal Use Tax. Write the marina a letter canceling your slip moorage and get an acknowledgement in writing from them. The County folks will not only check the marina's books
but walk the docks noting every vessel berthed there during their January walk through. I got trapped many years ago by holding onto my slip while I was cruising Mexico
for several years and when I tried to sort out the issue with the County Tax folks after they put a lien against my boat, the fact that I showed them continuous moorage receipts from Mexico from a number of marinas
through the years meant nothing to them. Their position was, 'pay the tax and penalties and if you fight it, you will pay more in attorneys fees
and court costs than your tax'. I took their advice. Had a similar experience on sales tax with the Franchise Tax Board. Even though I purchased the boat in Washington
State, cruised Canadian waters for 6 months before cruising down to San Diego
, they still felt I owed sales tax several years later. Fortunately, I had marina receipts, fuel
bills, and repair receipts to show that the vessel was indeed purchased out of state and remained out of state for over the required 3 months. It was difficult to reconstruct the entire stay outside of California but I eventually convinced them I was telling the truth and knew the law. I no longer live in California and am not interested in even visiting the state. Considering what they spend your tax dollars on, it is a good place to avoid.