WASHINGTON — Have a question for the Internal Revenue Service this tax season?

Good luck getting someone on the phone.

Only about one-third of those who called the IRS last year were able to get through, according to a new report by the Government Accountability Office. That’s much worse than in 2010, when about three-quarters of callers reached someone.

Average wait times for those who did manage to reach someone also tripled to more than a half-hour, according to the report by Congress’ watchdog.

Writing the taxman isn’t much help. The IRS didn’t respond to correspondence from taxpayers in a timely manner, and when it did, it often gave inaccurate information, the report said.

According to the report, the IRS, which has battled deep budget cuts, has no plans to fix the situation.

The report prompted denunciations of from members of Congress including Sen. Johnny Isakson, R-Georgia, a member of the Senate Finance Committee.

“This is what happens when you have a monopoly instead of a competitive environment,” he said in an interview.

Isakson has already been critical of IRS after a separate Inspector General’s report criticized it for rehiring hundreds of people who had performance or conduct issues when they previously worked there – including not filing their taxes.

He introduced a bill this week prohibiting the IRS from re-hiring people it has fired.

“The IRS has an abysmal record of customer service that is simply unacceptable,” said Indiana Sen. Dan Coats, also a Finance Committee member, in a statement about the report on poor phone service.

In a response to the Government Accountability Office, the IRS said many of its problems are due to the $1.2 billion in budget cuts it has weathered since 2010. The IRS would not comment on the report but instead pointed to its written response submitted to the GAO.

“The reality of our budget had an undeniable impact on the level of service and wait times for taxpayers who called for assistance,” wrote John Dalrymple, the IRS’ deputy commissioner for services and enforcement.

The GAO acknowledged the 10 percent budget cut as well as the strain of new problems faced by the IRS, such as preventing identity theft and Obamacare mandates that taxpayers report health care coverage.

In 2014, the IRS shifted $45 million from providing taxpayer services to improving online services, as well as efforts to combat refund fraud and improve cybersecurity.

As a result, IRS has about 1,000 fewer workers answering the phone. The agency also eliminated overtime during tax-filing season and shifted more workers to deal with a backlog of correspondence.

About 51 million people called the IRS last year - 6 percent fewer than in 2010.

But with about a third less IRS staff answering phones, the number of instances when callers just gave up increased 73 percent, the GAO said.

The IRS did reduce wait times for responses to correspondence, from 67.4 days in 2013 to 47 days last year. About 90 percent of those messages were accurate, the GAO found, though errors in not sending a required letter when a case was closed or giving incorrect dates and amounts due have increased.

The GAO also criticized the IRS for not implementing a number of recommendations, such as  coming up with a way to compare its customer-service practices with the private sector.

Dalrymple said IT charges at the IRS are meant to improve customer service. It would be difficult to compare to the private sector, he said, because companies do not face the same kinds of budget cuts or the tax-filing rush.

Still, Rep. Buddy Carter, R-Georgia, a member of the House Committee on Oversight and Government Reform, called the report on customer service an example of “unacceptable incompetence ... which has become the norm at the agency.”

Carter called for the removal of IRS Commissioner John Koskinen last July over allegations that the agency targeted conservative nonprofits.