The IRS incorrectly issued more than $46 million in refunds for tax year 2013, government inspectors discovered.

The Treasury Department released an internal audit Monday faulting a computer programming error and ineffective monitoring for the tens of millions in taxpayer dollars mistakenly refunded for returns covering tax year 2013.

The mistakes and shortcomings at the Internal Revenue Service could incorrectly drain up to $230 million from the Treasury during the next five years if left uncorrected, according to the report.

The review by the inspector general for tax administration found that the programming error overrode the IRS’ two-week processing delay placed on tax returns flagged as potentially fraudulent, automatically releasing over $27 million in returns before the IRS could verify the claims.

The inspector identified another $19 million in potentially fraudulent refunds doled out because of improper screening by IRS agents.

In a formal statement, Inspector General J. Russell George said:

While the IRS has made important strides in its programs that prevent the issuance of fraudulent refunds, our auditors found that it is not always ensuring that tax examiners timely complete their verification work before releasing refunds.

If the programming error isn’t fixed, it could result in the IRS’ issuing $135 million in mistaken refunds over the next five years, the audit concluded. Inspectors predicted the agency could release another $95 million in incorrect refunds “because tax returns are not being verified as required.”

Rep. Diane Black, R-Tenn., criticized the mistakes as “another reminder that the IRS is mired in incompetence and mismanagement.”

Black, who sits on the House Ways and Means Committee, called for the resignation of IRS Commissioner John Koskinen after a series of “stinging reports” revealed malpractice in the agency. In a statement Monday,  she said:

Just last week, my colleagues voted over my objections to give this bureaucracy another $290 million in the bloated omnibus bill. Only in Washington is this kind of ineptitude rewarded with a bigger check. … Taxpayers have every right to be outraged by the dysfunction at the IRS—I know I am.

The audit, dated Nov. 12, recommends the IRS fix the computer error and implement a process that ensures tax refunds flagged as potentially fraudulent are held until an IRS examiner has properly vetted the claim.