car tax?

I just bought a new car and car tax is due at the nd of this month. This is my second second-hand car after writing one off at the end of Novemeber. I had the car tax cover letter thourgh for the right off car at the begining of October dispite the fact it was due in Novemeber. I spoke to the guy I bought my new car from and he regerstered a changed of owner. Am I going to get it even though the date is getting later and later and if I don't what do I do?

Are you in the US?
New or used car?
So you haven't registered the car in your name yet?