So already funded and received my car, but in Texas I have to go register and pay the taxes at the Tax Office and get my reg sticker and plates. I had a trade in so I only have to pay the taxes on the sale price minus the trade in amount. What happens if anything, if you try to refinance at a lower rate before you even had a chance to register and pay the tax? Is there a chance the refi might cause you to taxes on the full sale price of the car? I've heard of CUs saying to wait until after your register your car or your first car payment before refinancing.