If both the U.S. and Belgian social security systems cover a worker’s employment or
self-employment, the agreement provides that beginning July 1, 1984, only one country’s
system will cover a worker’s employment. The agreement does not affect a worker’s
coverage prior to that date. If a worker had covered earnings under both the United
States and Belgium before July 1, 1984, those earnings would be subject to social
security taxes in both countries.