Certificates of coverage are the forms that SSA and the Polish authorities issue to
            workers who would otherwise have to pay Social Security taxes to both countries on
            the same earnings. A certificate issued by one country serves as proof that the worker
            named on the certificate is:
         
         
            - 
               
                  • 
                     subject to the laws of the country issuing the certificate, and 
 
 
- 
               
                  • 
                     exempt from Social Security coverage and contributions on the same earnings in the
                        other country.