Paul, you''re talking about the tax on your boat, correct? Your question is not about real property or intangible assets (savings & investments) or cars/trucks, right? And certainly not about Uncle Sam and any pension, investment or other income you have. As you suspect, Uncle has a long memory.
If we''re talking only about the boat, the issue for the Southeast U.S. is Use Tax. This is a tax assessed by the state in which you use the boat. In most states, use tax is wavied if you have paid a comparable sales tax on the boat when you purchased it; you have to prove this payment. If you paid less e.g. in NC when buying it than the FL tax rate permits, then FL would assess you the balance that they would see you owing them. OTOH if you paid no tax when acquiring the boat, they will attempt to collect the full amount.
Now that we understand the concept, the issue (for you) is how is it enforced. Usually, this is done via the state''s boat registration process; registering your boat obligates you to pay the tax. For U.S. documented boats (which yours apparently is, absent state registration) this is enforced by on-the-water state and county employees (e.g. marine police). They will look for a sticker you are supposed to display that shows you have ''registered'' your documented vessel and paid a small, annual fee...and the sticker is actually validating that someone in the state govt. has had the chance to check their records and confirmed (via info from another state or from you directly) that you owe no use nor sales tax. (Why is this an annual sticker & fee; why not a one-time fee? Well, even tho'' documented, they want a little revenue for your boat to be benefiting from the state''s services).
Computation of use tax is done differently by each state, tho'' the forumlae are pretty similar. If interested, talk to a local tax collector''s office ("I''m thinking of bringing me and my boat down here; what tax would I pay...etc."); don''t just rely on advice from folks like me on BB''s like this.
For you, the critical issue is where will you be cruising and how often (and where) will you be returning to the States. If you''re gone indefinitely, you are absent tax liability indefinitely. E.g. I register our documented boat in FL and have been told not to pay any annual fees nor file any paperwork until I return the boat to FL. Some parts of each state are more heavily patrolled than others; so far, you''ve been lucky. If stopped, you will be cited for violating the law (unless you have
fuel, marina or other receipts proving you have not been in that state longer than the state allows before imposing tax liability, usually 60 or 90 days). If you can''t prove that, then accept the citation and - assuming you are leaving that state or the USA soon thereafter - pay the fine (maybe $50) but not the tax. OTOH if you will be in that state''s waters indefinitely, it''s time to face the music.
Jack