It's important to clarify what you are talking about. Registration fees are only deductible if they count as a "state or local tax" and they must be based on the value of the car. For example, if the registration fee is $100 for everyone plus $1 per $1000 price of the car, and you buy a $35,000 car, your registration fee would be $135 but only $35 is considered a deductible state tax. This tax is only deductible in the year you pay it.
In addition, some states charge a personal property tax every year on the value of the cars you own. Again, this is a deductible state tax if it is based on the value of the car, but if the tax is calculated as a flat rate component plus a value component, only the value component is deductible. And again, this tax is deductible when you actually pay it.
If you paid one or both of these taxes in 2024, it would have to be included on your 2024 tax return.
Your deduction for state and local taxes are capped at $10,000, so if your taxes are already more than that, you won't get any benefit for adding the car fees and taxes.
