Australia will not issue a certificate of coverage in situations involving the general
rule for employment (RS 02002.010), the crews of ships and aircraft rule (RS 02002.020) or the self-employment rule (RS 02002.030). In those situations, a letter of exemption must be obtained from SSA. A letter
of exemption issued by SSA certifies that the worker (and employer, if employed) is
subject only to Australian law under the agreement, regardless of whether or not contributions
must be made under Australian law, and is therefore exempt from U.S. Social Security
and Medicare taxes.