Va. Code § 58.1-2406
In the event any person submits with his application for a certificate of title a sum insufficient to pay the sale or use tax as determined by the Commissioner, it shall be the duty of the Commissioner or his authorized agent to make an estimate of the tax due the Commonwealth and to assess such tax. The notice of assessment shall be forthwith sent to such person by certified mail at the address of the person as it appears on the records of the Division. Such notice, when sent in accordance with these requirements, shall be sufficient regardless of whether or not it was ever received.
If any person fails to pay such tax, the Commissioner shall bring an appropriate action for the recovery of such tax plus interest. Judgment shall be rendered for the amount of the tax found to be due together with interest and costs.
Va. Code § 58.1-2406