D.C. Mun. Regs. tit. 27, r. 27-3250
A contractor may assign moneys due or to become due under a contract if all the following conditions are met:
Unless otherwise expressly permitted in the contract, an assignment shall cover all unpaid amounts payable under the contract.
Unless expressly permitted in the contract, an assignment may be made only to one (1) party, except that any assignment may be made to one (1) party as agent or trustee for two (2) or more parties participating in the financing of the contract.
Unless expressly permitted in the contract, an assignment of contract payments shall not be subject to further assignment.
The assignee shall be required to send written notice of assignment together with a true copy of the assignment instrument to the following in accordance with § 3251.4:
A contract may prohibit the assignment of contract payments if the contracting officer determines that the prohibition is in the best interests of the District.
Under a requirements or indefinite quantity type contract that authorizes ordering and payment by multiple District agencies, amounts due based on estimated quantities may be assigned.
The District may apply against payments to the assignee any liability of the contractor to the District arising independently of the assigned contract if the liability existed at the time notice of the assignment was received even though that liability had not yet matured so as to be due and payable.
D.C. Mun. Regs. tit. 27, r. 27-3250