D.C. Code § 47-1805.02b: Transition from the Joyce method of apportionment to the Finnigan method of apportionment.

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.