When writing checks to the Internal Revenue Service, taxpayers might wish Uncle Sam had a much smaller appetite. Yet they know that putting him on a severe diet means Sam can’t get his job done.

The diet Congress has imposed on the IRS means taxpayers not only have to pay up, but they also have to put up with additional hassles. Cuts to IRS staff mean cuts in service to taxpayers.

That’s the message Nina Olson, the national taxpayer advocate, delivered to a House Appropriations subcommittee Wednesday. She described an agency with stark declines in customer service.

“From January first through February 14th this year, the IRS answered only 43 percent of the calls it received from taxpayers seeking to speak with a customer service representative, and those taxpayers who managed to get through sat on hold an average of about 28 minutes,” she said. “By comparison, during the same period last year, 77 percent of taxpayers got through and waited on hold an average of about 10 minutes. The IRS is now only answering the most basic of tax-law questions through April 15, and none after that. And it is no longer preparing tax returns for the most vulnerable taxpayer populations: elderly, disabled and low-income.

“This performance decline is huge and results from a combination of more work and reduced resources,” Olson said.

More work — “The IRS is receiving 11 percent more returns from individuals, 18 percent more returns from business entities, and 70 percent more telephone calls through fiscal year 2013 than a decade ago,” she said.

Reduced resources — “The IRS’s budget has been reduced by about 17 percent in inflation-adjusted terms since FY 2010,” which she said so far has resulted in almost 12,000 fewer employees, a 12.3 percent drop. There are projected cuts of several thousand more during this fiscal year.

This adds up to “the worst levels of taxpayer service since at least 2001, when the IRS implemented its current performance measures,” Olson said.

David Carrone, a revenue agent in New Orleans and a chapter president of the National Treasury Employees Union, sees that “every single day.”

“At a certain level we have to turn people away because we don’t have the staffing to handle it. It’s a sad situation,” he said. In almost 29 years with the IRS, “this is the worst I’ve ever seen it.”

Budget cuts lead not just to longer lines, but also to lower tax collections.

J. Russell George, the Treasury inspector general for tax administration, told the subcommittee that “budget cuts have resulted in significant declines in the performance of the IRS collection program.”

Keep this in mind. Each dollar spent on tax enforcement actions in 2016 is expected to bring in more than $6. Where else can you get that return on investment?

Yet, the IRS situation might get worse for employees before it gets better.

Because of budget cuts, IRS Commissioner John Koskinen warned employees last month that they could be furloughed for two days this year to save money.

With taxes needed to run the government and since each dollar spent returns a few more, you might think lawmakers would have no problem adequately funding the IRS.

But not the Republicans who felt a need to punish the agency by sending it to bed without its supper.

“While the IRS has exhibited a litany of questionable practices and expenses over the past five years with regards to processing tax-exempt applications, bonuses, conferences, videos, and now hiring, what I really want to hear today is how, or if, the IRS has or could change its ways,” said Rep. Ander Crenshaw (R-Fla.), the Financial Services and General Government Appropriations subcommittee chairman.

“We deliberately lowered the IRS funding to a level to make them think twice about what they were doing and why,” he added. “They don’t have a dime to spare on anything frivolous or foolhardy or even middling. The IRS should and must focus on the most important, the most egregious, and the most in need.”

Olson acknowledged that like any agency “the IRS can operate more effectively and efficiently in certain areas. However, I do not see any substitute for sufficient personnel if high-quality taxpayer service is to be provided,” she said. “The only way the IRS can assist the tens of millions of taxpayers seeking to speak with an IRS employee is to have enough employees to answer their calls. The only way the IRS can timely process millions of taxpayer letters is to have enough employees to read the letters and act on them. And the only way the IRS can meet the needs of the millions of taxpayers who visit its walk-in sites is to have enough employees to staff them.”

But for now, those taxpayers will have to wait for service, then wait some more.

“It is time for Congress to put taxpayers first,” said NTEU President Colleen M. Kelley, “and give the IRS the resources it needs to serve the public.”

Twitter: @JoeDavidsonWP

Previous columns by Joe Davidson are available at wapo.st/JoeDavidson.