In one of her last acts as Treasury Secretary, Janet Yellen said her agency will start taking “extraordinary measures,” or special accounting maneuvers intended to prevent the nation from hitting the debt ceiling,

Janet L. Yellen, the outgoing Treasury secretary, urged lawmakers to raise the debt limit and protect the full faith and credit of the United States.

Treasury Secretary Janet Yellen, in a letter on Friday to congressional leaders, said the Treasury would begin using extraordinary measures Jan. 21.