Per the Virginia Department of Taxation:
Effective July 1, 2011, every withholding tax filer with a semi-weekly filing status is required to file all withholding tax returns and payments electronically. This requirement does not change the filing frequency requirements; however, it may change the filing and payment method used. While some semi-weekly filers are currently required to make their VA-15 payments electronically, this new mandate now requires their VA-16 and VA-6 returns and payments to be filed electronically as well. Employers can meet these electronic filing and paying requirements without purchasing tax filing software. VATAX offers several online services at no cost : Business iFile, Web Upload, ACH Debit and ACH Credit.
W-2 Filing: Electronic Filing Requirement