Register for the SSA Business Services Online (BSO) SSNVS service using employer EIN and an authorized representative
Prepare a batch file with up to 250,000 name and SSN pairs per the SSNVS batch file format specification
Submit the batch file through the BSO SSNVS interface and record the submission confirmation number
Download the results file within 24 hours, parsing the verification result code for each record (verified, SSN not in file, name/SSN mismatch, death record)
Flag employees whose SSN does not verify for HR follow-up before processing their first payroll; document the discrepancy and resolution per IRS guidance
Known gotchas
SSNVS results reflect SSA records as of the prior business day; recently issued SSNs may not yet appear in the database
A mismatch result does not necessarily indicate fraud; name changes, hyphenation differences, or data entry errors are common causes and must be investigated before taking adverse action
SSNVS may only be used for payroll tax purposes; using results for any other purpose such as credit screening or background investigations violates the terms of service
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