Can I use a car registration fee for a 2017 tag that I purchased late to my registration fee for a 2018 tag for deductions?

[MichaelDC]

It's hard to tell what the issue is without knowing more about your return. In general, we can only claim deductions in the year paid, not the year due or the year to which the payment applies. If the payment was made in 2017, you can claim it on the 2017 return. If one was made in 2018, that will be deductible on the 2018 return. Please feel free to post any additional details or questions in the comment section. 

Secondly, you need to make sure that your registration fees is deductible in your state:

https://ttlc.intuit.com/replies/6145391