The defintion of a Service contract (FAR subpart 22.1001 Defintiions) means any Government contract , the principle purpose of which is to furnish services in the United States through the use of service employees............

If I have a contract that is primarily providing services in a foreign country in support of an FMS contract then is my contract subject to the Servcies Contract Act?

See FAR 22.1003-2

22.1003-1 -- General.

This Subpart 22.10 applies to all Government contracts, the principal purpose of which is to furnish services in the United States through the use of service employees, except as exempted in 22.1003-3 and 22.1003-4 of this section, or any subcontract at any tier thereunder.

Without more details, my read would be that a portion (that which is furnishing services in the U.S.) would fall under SCA; the portion performed outside the U.S. would not fall under the SCA.

The big question is trying to determine which portion is and isn't. And please keep in mind, when I was stationed in Panama, we also incorporated host nation requirements into our contracts.

I have handled FMS contracts and other contracts requiring performance overseas. While it may be exempt from the SCA, your contract may be covered by the Defense Base Act. Take a look at FAR 28.305.

See also DFARS SUBPART 222.72--COMPLIANCE WITH LABOR LAWS OF FOREIGN GOVERNMENTS.