It has been my experience that when i buy a vehicle/boat/trailer in one state, then move to or register in another state, I have paid sales tax again on the value declared when purchased based on the state and what i had previously paid. For example, when i bought my truck in Texas and moved to Florida, I paid sales tax in Texas at 8%, when i moved to Florida, the rate was 8.5% so they charged me the ,5% difference. When I brought the same truck to washington, They charged me sales tax based on the current Blue Book Value. Long story short, I have paid sales tax on a vehicle 3 times and I only purchased it once. Like others said before, It all depends on the State and the Tax Collectors interpration of the statue.