Exception for mirror code possessions
In the case of a possession of the United States which has a mirror code tax system (as such terms are defined in section 272(c) of the COVID-related Tax Relief Act of 2020), no refund or credit shall be made or allowed under this subsection after the earlier of—
(aa)#
such date as is determined appropriate by the Secretary, or
(bb)#
September 30, 2021 .