How do I find out how much I paid for vehicle registration fees?

If you have no bill from your state or record of payment, you probably had to contact your state's Department of Motor Vehicles. 

You may be interested to know that it typically is a rather small deduction and only used if you itemize (report a house mortgage, property taxes, high charitable donations, etc.) Consequently, by itself, it might not be helpful to you.

If you have any other details regarding this question, please feel free to post them in the comment section. 

More info: If you paid registration fees to a state that charges a tax based on the vehicle's value, you might be able to claim the deductible value-based (sometimes, ad valorem) portion of your registration fee. Every state has its own way of calculating the registration fee on a vehicle, and those calculations typically take several factors into account. For example, say your annual car registration fee is based on a formula that charges $2 per 100 pounds of vehicle weight, $1 per $1,000 of value, a flat $10 for license plate tabs, and $35 in other taxes and charges. If you had a 4,200-pound vehicle with a value estimated by the state at $25,000, then your fee would be $154 ($84 plus $25 plus $10 plus $35). Of that, only $25 would be an itemized deduction, because that's the only portion based on the actual value of the vehicle.