It's Good, This Allowance, It Services

Pay me more, or less.

Goods and services allowance: A payment made to reimburse an expatriate for the difference between the costs of goods and services at home versus on assignment.

It is often used for offsetting higher overseas prices of non-housing goods and services.

In U.S. government service, this amounts to around a total of $2 billion every year.

It is designed so employees (a.k.a. "service members") can get the same level of goods and services overseas as they could if they were stationed inside the continental United States (which they call "CONUS"), and fluctuates with the relative difference in the cost of living. So there.