SSNVS = The Social Security Number Verification Service 

There are two Internet verification options you can use to verify that your employee names and Social Security numbers (SSN) match Social Security’s records. You can:

Verify up to 10 names and SSNs (per screen) online and receive immediate results. This option is ideal to verify new hires.

Upload overnight files of up to 250,000 names and SSNs and usually receive results the next government business day. This option is ideal if you want to verify an entire payroll database or if you hire a large number of workers at a time.

While the service is available to all employers and third-party submitters, it can only be used to verify current or former employees and only for wage reporting (Form W-2) purposes.