(Bloomberg) -- The US government added $347 billion to the deficit in May, up 5% over the same month last year, as elevated borrowing costs continued to drive the growth in spending.

That brought the year-to-date shortfall to $1.2 trillion, slightly lower than for the first eight months of fiscal year 2023, according to data released Wednesday by the Treasury. All the comparison figures are adjusted for calendar differences.

Receipts for the fiscal year are so far running 9% higher than last year, helped by a 29% jump in gross corporate taxes. Those numbers, however, are somewhat inflated by deadlines that were pushed back from 2023 into the current fiscal year for taxpayers in California and other areas affected by natural disasters. 

On a call with reporters, a Treasury official said the department is not yet able to provide an estimate for how much the deadline extensions have distorted the year-over-year comparisons for revenue.

On the spending side, year-to-date outlays for interest paid on public debt reached $728 billion, a 37% increase over last year. Total outlays for the fiscal year grew an adjusted 6% to $4.5 trillion.

Spending in May was $671 billion, up 6% over the same month last year.

The Federal Reserve’s aggressive interest-rate hiking campaign — aimed at quelling high inflation — has made debt more expensive. The weighted average interest rate on US total marketable government debt was 3.3% at the end of May — the most expensive since 2008 and roughly 60 basis points higher than a year before.

Outlays for Social Security and defense spending, each up 8%, added a combined $115 billion to the deficit through May.

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