It depends.
Once you figure out which part is deductible (see below), then you can add them together when you enter them.
Car registrations deductions are a bit tricky.
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.
Annual fees
To be deductible, a value-based auto registration fee must also be assessed on an annual basis. What matters here is the frequency with which the tax is charged to you, not the frequency with which it's actually collected. A state could collect half of the fee every six months, for example, or allow you to pay two years' worth of fees at a time, but you can still take a deduction as long as the fees are assessed on a per-year basis.
Taking the deduction
To deduct the value-based portion of your registration fee, you must itemize your deductions using federal Schedule A. Car fees go on the line for "personal property taxes." Note that your state might not specifically refer to the fee as a personal property tax. Nevertheless, if the fee is value-based and assessed on a yearly basis, the IRS considers it a personal property tax.
