Tanisha Keller, a single mother who works for the federal Census Bureau, used to live paycheck to paycheck. Now, she is living nothing to nothing.

Payday would have come this week for Ms. Keller, 42, and many of the 800,000 other federal workers across the country caught up in the partial government shutdown. But as the standoff drags on, no paychecks are arriving to replenish their savings or pay down their maxed-out credit cards.

Ms. Keller’s bank balance has dipped to negative $169. She can no longer afford the $100 stipends she once sent to her son, Daniel, to help out with his college books and groceries. She does not know how she will make next month’s $1,768 rent on her apartment in Waldorf in Southern Maryland, or how she will cover the bills that automatically debit from her checking account, or even how she will gas up the car she has been trying not to drive.