or produced (or which would have been imposed by such subsection on such other fuel but for section 4691(c)). 4693. Border adjustments (a) Imports The Secretary shall impose a carbon equivalency fee on imports of carbon-intensive goods that shall be equivalent to the cost that domestic producers of comparable carbon-intensive goods incur as a result of— (1) taxes paid by manufacturers, producers, and importers of taxable carbon substances under this section, and (2) carbon equivalency fees paid by importers of carbon intensive goods used in the production of the comparable carbon intensive goods in question. (b) Exports Notwithstanding the limitations of section 4692, the Secretary shall allow as a credit or refund (without interest) to the exporter of a carbon-intensive good produced in the United States in the same manner as if it were an overpayment of tax imposed by section 4691 an amount equivalent to the cost that domestic producers of such carbon intensive goods incur as a result of— (1) taxes paid by manufacturers, producers, and importers of taxable carbon substances under this section, and (2) carbon equivalency fees paid by importers of carbon intensive goods used in the production of the comparable carbon intensive goods in question. (c) Expiration This section shall cease to have effect at such time as and to the extent that— (1) (A) an international agreement requiring countries that emit greenhouse gases and produce carbon intensive goods for international markets to adopt equivalent measures comes into effect, or (B) the country of export has implemented equivalent measures, and (2) the actions provided for by subsections (a) and (b) are no longer appropriate. 4694. Definitions and special rules (a) Definitions For purposes of this subchapter— (1) Taxable carbon substance The term taxable carbon substance means— (A) coal (including lignite and peat), (B) petroleum and any petroleum product (as defined in section 4612(a)(3)), and (C) natural gas, which is extracted, manufactured, or produced in