A Jan. 14 audit of the IRS's purchase card program found instances of potential misuse or fraud that had gone unreported by the agency, including an employee buying a pair of tablet computers and concealing the purchase.

The report, part of a semiannual audit of the IRS purchase card program, found that the agency had adequately documented 13 confirmed cases of misuse and an additional two cases that were awaiting final agency action.

Related: Read the report

Twelve of the cases totaled almost $600, which was used to buy prohibited items like hand sanitizer, tissue and bottled water for the office, while another case found an employee transaction for personal use. The report said that $315 of charges related to the purchases was credited back to charge card accounts through returns and repayments.

But the IRS didn't find was $2,350 in charges made by a single employee, including buying two electronic tablets and 37 suspicious purchases at Amazon and Office Depot.

The charges, discovered by a Treasury Inspector General for Tax Administration audit not related to purchase card misuse, found that the employee in question falsified receipts to hide the tablet buy in July 2011.

The employee later resigned, and was later charged with grand theft for the purchases and was sentenced to three years of probation in May 2015.

TIGTA also turned up four other cases of potential card misuse, one of which is still under investigation.

The remaining three cases involved buying office supplies like keypads, toner cartridges and keyboards without going through the acquisition and approval process. The audit stated the IRS deemed the cases to be "administrative in nature", but since there has yet to be a final determination on the case, TIGTA decided to include them in the audit.

TIGTA also found that the IRS had adequately updated its internal controls in 2015 to mitigate the risk of fraud and misuse of the charge card program. The agency said it also planned to institute additional oversight reviews of charge card purchases.

The audit also addressed a previous TIGTA recommendation of instituting policies for employees who had previously misused agency charge cards, including reporting them to security personnel to determine whether their security clearances, background checks and even employment should be reevaluated.

The recommendation called for reevaluation policies when evidence of "significant personal financial problems" was present.

The recommendation was supposed to be implemented by September 2014, but the IRS initially disagreed with it and then asked for an extension until September 2015 to carry it out.

As of December 2015, the recommendation remains open, as the IRS has stated that new disciplinary action must be collectively bargained with employee unions before being implemented. TIGTA said it still supports the recommendation.

The report offered no new recommendations, and the IRS agreed with the facts in the report.