May 10 (Reuters) - The U.S. federal budget surplus in April increased from a year earlier as a boost in tax receipts outpaced a rise in outlays, the Treasury Department said on Friday.

The surplus last month was $210 billion, up 19% from the $176 billion surplus in April 2023. Outlays rose 23% to $567 billion.

Receipts increased 22% to $776 billion due to higher tax revenue from individuals and businesses. Economists polled by Reuters had expected a surplus of $244 billion in April.

For the first six months of the fiscal year, the deficit shrank by $70 billion, or 8%, to $855 billion. Receipts were up 10% to $2.964 trillion during that period while outlays rose 6% to $3.819 trillion.

A big driver of the outlays continued to be interest costs on the national debt, which rose 36% on a year-to-date basis to $624 billion, second only to the Social Security program for seniors in individual line item expenses. For April alone debt-servicing costs were $102 billion, up 35% from the year-earlier period.

Individual tax refunds, which are deducted from receipts, were $1 billion higher, up 2% from 12 months earlier. Individual withheld receipts in April were up $50 billion, or 10%, from a year earlier. (Reporting by Lindsay Dunsmuir; Editing by Paul Simao)