D.C. Code § 47-1810.06
As a filing convenience, and without changing the respective liability of group members, members of a combined reporting group shall designate one taxpayer member of the combined group to file a single return, in the form and manner prescribed by the Chief Financial Officer, in lieu of filing their own respective returns; provided, that the taxpayer designated to file the single return consents to act as surety with respect to the tax liability of all other taxpayers properly included in the combined report and agrees to act as agent on behalf of those taxpayers for tax matters relating to the combined report. If for any reason the agent is unwilling or unable to perform its responsibilities, tax liability may be assessed against the taxpayer members.
D.C. Code § 47-1810.06
Section 8004 of D.C. Law 19-21 provided: "Sec. 8004. Applicability. This subtitle shall apply for taxable years beginning after December 31, 2010."
Applicability of D.C. Law 20-61: Section 7103 of D.C. Law 20-61 provided that § 7102 of the act shall apply for taxable years beginning after December 31, 2010.