Register for SSA Business Services Online (BSO) and enroll for the W-2 Online or file upload service using the employer EIN
Build the EFW2 fixed-width file with RA (submitter), RE (employer), RW (employee wage), RO (optional employee wage supplemental), RS (state wage), and RF (final) records per the current SSA EFW2 publication
Validate the file using SSA's AccuWage Online tool to detect format errors before submission
Upload the EFW2 file via the BSO wage file upload interface and capture the submission receipt number and confirmation email
Resolve any SSA reject notices (error code list) within the BSO portal and resubmit corrected files before the annual filing deadline
Known gotchas
EFW2 field positions are fixed-width and zero-padded; any off-by-one positional error silently corrupts every subsequent field in the record
The AccuWage validation tool catches format errors but not data accuracy issues such as incorrect Box 12 codes or missing state wage records
Employers with 250 or more W-2s are required to file electronically; paper filing for large employers is rejected and subject to penalties
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp