5 CFR § 591.231
Which areas are post differential areas?
November 4, 2020
OPM has established the following post differential areas:
(a) American Samoa as defined in §591.205,
(b) Territory of Guam,
(c) Commonwealth of the Northern Mariana Islands,
(d) Johnston Atoll (including Sand Island),
(e) Midway Atoll, and
(f) Wake Atoll.