The Generalized System of Preferences (GSP) provides duty-free treatment to goods of designated beneficiary countries. The program was authorized by the Trade Act of 1974 to promote economic growth in the developing countries and was implemented on January 1, 1976.
The GSP periodically expires and must be renewed by Congress to remain in effect. The 2015 GSP reauthorization (H.R. 1295) expired on December 31, 2017.
On Friday, March 23, 2018, the President signed into law H.R. 1625, the “Consolidated Appropriations Act, 2018,” which in addition to providing full-year federal appropriations through September 30, 2018, extended GSP with retroactivity, from January 1, 2018, through December 31, 2020.
Importers should continue to flag GSP-eligible importations with the SPI “A” and pay normal trade relations (column 1) duty rates until the effective date of the Act, April 22, 2018, at which time programming will obviate the duty payment.
If your entries have already been subject to GSP and filed with SEWW as your agent , your GSP Duties have been flagged with the SPI "A". For more information, CBP.GOV