Payment due for vehicles purchased or moved into the county and registered with Fairfax County on or after July 1 of the prior year. Most personal property tax bills are due October 5.Please have your account number and payment amount ready. Payment services on this site offer a convenient and secure option to pay your taxes. The tax balances on the online search system may not reflect adjustments. Simply fill in the required fields, and pay any tax due using direct debit. You will hear your current account balance and due date, as well as last payment date and last payment amount. For residential properties in Fairfax County, tax payments work in a series of two installments due on July 28 and December 5 of each year. The remaining estimated payments would be due on December 15, March 15 and July 15 of the succeeding taxable year.