D.C. Code § 47-1805.02b
For tax years beginning after December 31, 2025, a combined group of entities will be treated as one taxpayer for purposes of sourcing unitary receipts, as required by this chapter, and the apportionment factor attributes in the numerator, as required by this chapter, will be derived from all the members of the combined group, regardless of whether a member has nexus with the District of Columbia.
For temporary (90 days) creation of this section, see § 7002(b) of Fiscal Year 2025 Budget Support Emergency Act of 2024 (D.C. Act 25-506, July 15, 2024, 71 DCR 8406).
Sept. 18, 2024, D.C. Law 25-217, § 7002(b)