Juliegrace Brufke on April 18, 2016 at The Daily Caller News Foundation

April 18 marks the deadline for Americans to file their taxes – a day most people dread. In honor of the closure of tax season, here’s a look at the Internal Revenue Services’ biggest failures.

1. Taxpayers remain at risk for identity theft

Despite warnings from government watchdogs, the IRS’ security controls aren’t strong enough to protect taxpayers’ personal information, according to a recent report released by the Government Accountability Office (GAO).

The audit found the vulnerabilities were largely due to the agency’s failure to effectively implement systems it had in place and continued to use outdated, unsupported software on a system used to access and manage taxpayer accounts.

It was also discovered the agency failed to fully develop, document and update several security policies, including: controls for authenticating and identifying users, ensuring that sensitive authentication data is encrypted, monitoring systems to make sure they comply with IRS policies and ensuring only authorized employees had access to restricted areas.

2. IRS Customer service is absolutely appalling 

The GAO found phone calls from those wanting help with their taxes often went unanswered or suffered excessively long wait times.

While the IRS slightly improved its service from 2015, the 26-minute average hold time is nearly twice as long as fiscal year 2011, according to the watchdog’s report.

3. They have been found to hire back employees that were fired for misconduct

GOP lawmakers have had to go so far as to introduce legislation to prevent the government agency from hiring back employees fired for reasons including: fraud, falsification of documents, and unauthorized access to taxpayer information

Treasury Inspector General for Tax Administration found the agency mistakenly rehired around 300 employees who were previously asked to leave their posts for “substantiated employment issues” between 2010 and 2013.

4. The agency still runs the risk of targeting groups based on political ideology 

Despite the Lois Lerner scandal involving the agency’s reported targeting of certain groups for their political ideologies, the IRS has yet to implement proper internal controls to prevent similar incidents from reoccurring.

“The control deficiencies increase the risk of selecting organizations for audit in an unfair manner—for example, based on an organization’s religious, educational, political, or other views. We recommended that IRS take 10 actions to improve selection control design and implementation, to which IRS generally agreed. Similarly, in July and in September 2015,” a December 2015 report by the GAO reads. “We found that IRS did not clearly define program objectives and key terms in its collection programs, which could undercut IRS’s ability to assess risks and monitor performance.”

5. It’s failed to implement a system preventing illegal immigrants from filing under phony Social Security numbers 

While testifying before Congress, IRS Commissioner John Koskinen told lawmakers the agency isn’t coming down on illegal immigrants using fraudulent Social Security numbers because it’s “everybody’s interest to have them pay the taxes they owe,” the Washington Examiner reports.

At a 2015 hearing, Koskinen admitted those residing in the country illegally who didn’t pay taxes are able to receive refunds once they receive Social Security numbers.