It appears to be 20 years. See below:
Tax Code of Virginia
Code Section: 58.1-1802.1 Tax Type: General Provisions Brief Description: Period of limitations on collection; accrual of interest and...
Depends on the type of tax, but in income taxes, anyplace...the Statute of Limitations for assesment and Collection (normally 3-4 years) ONLY STARTS running when a return has been filed. If you don't...