D.C. Mun. Regs. tit. 9, r. 9-107
Returns shall be filed by every unincorporated business engaging in or carrying on any trade or business within the District or receiving income from sources within the District having a gross income of more than twelve thousand dollars ($ 12,000) regardless of whether or not it has a net income.
For purposes of this section, the meaning of "gross income" shall be gross revenue from all District sources before deduction of cost of goods, expenses, and other allowable deductions permissible in the determination of net income.
The return of an unincorporated business shall be made by the taxpayer or the taxpayers liable for the payment of the tax.
The tax imposed under the Act may be assessed in the name of the unincorporated business or in the name or names of the person or persons liable for the payment of the tax, or both.
D.C. Mun. Regs. tit. 9, r. 9-107