Almost 1,600 IRS employees willfully evaded their taxes over a 10-year period, but most were allowed to keep their jobs - some were even promoted, according to a new inspector general report released Wednesday.

The offenses included improperly claiming dependents, repeated failure to file timely tax returns, and claiming a tax credit for first-time homebuyers when no house was actually purchased.

Despite a 1998 law calling for the termination of any IRS worker who willfully doesn't pay their taxes, the IRS refused to fire about 60 percent of the willful violators. Some even received promotions, raises and bonuses after they were caught, according to the report.

"Given its critical role in federal tax administration, the IRS must ensure that its employees comply with the tax law in order to maintain the public's confidence," said J. Russell George, Treasury inspector general for tax administration, reported The Associated Press. "Willful violation of the law by IRS employees should not be taken lightly, and the IRS commissioner should fully document decisions made to retain employees whom management has proposed be terminated."

The IRS identified some 13,000 suspected cases of tax violations committed by its own employees between 2004 and 2013. The report found that 1,580 of those were intentional violations. Of those, 108 received no punishment at all, while others were reprimanded or suspended. Others were sent to counseling, while some were given the option to resign or retire. In all, only 39 percent left the agency.

The IRS said that 99 percent of its 85,000-strong workforce pay their taxes on time, which is the highest compliance rate of any major federal agency, according to AP.

"The IRS is committed to ensuring that employees meet their tax compliance responsibilities," the IRS said in a statement, reported The Washington Times. "Nonetheless, the IRS agrees that we can improve this process. The changes will include a more proactive approach to ensure timeliness and consistency and provide more transparency in the mitigation process while preserving the commissioner's authority provided by federal law."