Down with the IRS! Up with tax cheats, government dysfunction and nonexistent customer service! (Jonathan Ernst/Reuters)

Congress has done some dumb things. One of the dumbest is the GOP’s penny-wise-pound-foolish campaign to defund the Internal Revenue Service. We now have official word about what its mindless tantrum against the IRS has produced for taxpayers: a tax season that was “by far the worst in memory,” according to the Taxpayer Advocate Service, an agency watchdog.

“The IRS’s performance in responding to taxpayer telephone calls this year was, as IRS Commissioner Koskinen has acknowledged, ‘abysmal.’ During the filing season, the IRS was only able to answer about 37 percent of the calls routed to telephone assistors, and those callers who managed to get through had to wait on hold an average about 23 minutes.”

Meanwhile, “The number of courtesy disconnects” — that is, hangups — “skyrocketed this filing season as compared with prior years, rising by more than 1,500 percent from about 544,000 in 2014 to about 8.8 million this year.”

Even when people got through, IRS customer service agents were allowed only to answer some basic tax questions, and they couldn’t say anything about tax law.

The report didn’t even touch on the massive amounts of money that the government will lose from degraded tax enforcement, which rewards tax cheats. Republicans warn about the United States emulating Greece, apparently ignoring the fact that lax tax-collecting has been a major driver of the fiscal problems there.

The underlying problem is that Congress has asked the IRS to do a lot more, such as administering a critical piece of Obamacare, but the GOP Congress won’t give the agency the funding it needs to do its work. “When an organization is given more responsibility and its budget is simultaneously reduced by about 17 percent on an inflation-adjusted basis, its performance almost inevitably will suffer,” the taxpayer advocate said. “To improve taxpayer service, the IRS will need more resources to answer taxpayer telephone calls, process and respond to taxpayer correspondence, and assist taxpayers who seek assistance in its walk-in sites.”

Maybe the budget wasn’t to blame. Maybe the IRS was just being lazy? Too busy persecuting conservative advocacy organizations? Or, worse, calculatedly inflicting pain on taxpayers in a play to get more funding? Not according to the advocate’s analysis: “Under these difficult circumstances, the IRS accomplished a great deal. It received and processed most tax returns in a timely manner, and it issued timely refunds to most taxpayers who were entitled to them.” It just didn’t have the staffing to offer much assistance to anyone who needed help.

But good luck convincing Republicans to fix the IRS’s entirely predictable and avoidable problems. Not when that would mean restraining the impulse to act on anti-tax orthodoxy, blind populist anger and scandal-mongering about the IRS mistreating conservatives. In fact, Republicans want to double down on their nonsense budgeting, proposing deep cuts to the IRS last month. Though they moved to improve telephone support, their proposed cuts would obviously degrade services and effectiveness in other areas. The underlying irrationality is the same: The IRS doesn’t write the tax code or health-care law, but the agency must apply these policies and engage with people affected by them, so it is an easy scapegoat. Policy dysfunction, rewarded lawbreaking and a raw deal for average taxpayers is the result.

UPDATE, 11:04 a.m.: Slight edits made above for clarity.