Per IRS Form 8924, page 2:
An eligible entity who subsequently transfers ownership or possession (by sale, exchange, or lease) of a qualifying mineral or geothermal interest must file Form 8924 for each transfer of an interest acquired, directly or indirectly, in:
Section 403 of Title IV, Division C, of the Tax Relief and Health Care Act of 2006 has more details, including the geographic location of eligible federal land.
25% exclusion from gross income is allowed for long-term capital gain from certain conservation sales of qualifying mineral and geothermal interests located on eligible federal land. The sale must be to an eligible entity and occur after December 19, 2006. An excise tax may be imposed if an eligible entity fails to take steps consistent with the protection of conservation purposes.
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