That compared to a budget deficit of $13.5 billion in the same month the year earlier, according to the Treasury's monthly budget statement.

Analysts polled by Reuters had forecast a $15 billion deficit for the month.

Unadjusted receipts last month totaled $336 billion, up 7% from December 2018, while unadjusted outlays were $349 billion, also a rise of 7% from the same month a year earlier.

When adjusted for calendar effects, the deficit for December was $40 billion compared with an adjusted deficit of $35 billion in December 2018.

(Reporting by Lindsay Dunsmuir; Editing by Andrea Ricci)