A certificate of coverage certifies that SSA has determined that a worker's employment
            or self- employment in an agreement country is covered by the U.S. system under terms
            of the applicable agreement. Each certificate:
         
         
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                  • 
                     identifies the worker and his employer or the type of self-employment, and 
 
 
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                  • 
                     shows the period for which it is valid. 
 
 
Most certificates show both a beginning date and an ending date. Under some agreements
            an ending date may not be shown; in such cases, the certificate is valid indefinately.