IRS Commissioner John Koskinen. (AP Photo/J. Scott Applewhite).

The head of the Internal Revenue Service this week told House appropriators that austerity is taking its toll on tax enforcement and customer service at his agency, making a case for more funding as President Obama prepares to release his 2015 budget proposals on March 4.

IRS Commissioner John Koskinen testified Wednesday before a House appropriations subcommittee that staffing and resources have become a major concern at his agency, saying the IRS is likely to miss 18 million taxpayer calls and billions of dollars in enforcement revenues.

“I hope that one of my legacies at the end of my four years as IRS commissioner will be that we put the agency on a more solid and sustainable funding level,” Koskinen said.

Republicans on the panel blasted the commissioner for reinstating tens of millions of dollars in performance awards this month after his predecessor, Daniel Werfel, decided to cancel the bonuses last year due to budget constraints under the government-wide spending cuts known as the sequester.

MORE: IRS reinstates employee bonuses, ending sequester-related hold on awards

“What I find unacceptable is that in this $11.3 billion appropriation that the IRS received this year, that you can’t find the money to answer more than half the phone calls and yet you can find the money to pay $63 million in bonuses,” said Rep. Ander Crenshaw (R-Fla.), the chairman of the subcommittee.

Koskinen downplayed the awards, saying about two-thirds of the IRS’s 90,000 employees typically receive them and that the average amount is about $1,200. He also noted that the agency paid a lower rate than its collective-bargaining agreement called for, offering 1 percent of salaries rather than 1.75 percent.

The budget that Congress and the president approved in December provides agencies with limited relief from the sequester, but the IRS is still $900 million short of its funding level from four years ago.

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