The cuts are depleting the staff members who help ensure that taxpayers pay what they owe. As of last year, the IRS had 9,510 auditors. That’s down a third from 2010. The last time the IRS had fewer than 10,000 revenue agents was 1953, when the economy was a seventh of its current size. And the IRS is still shrinking. Almost a third of its remaining employees will be eligible to retire in the next year, and with morale plummeting, many of them will.

The IRS conducted 675,000 fewer audits in 2017 than it did in 2010, a drop in the audit rate of 42 percent. But even those stark numbers don’t tell the whole story, say current and former IRS employees: Auditors are stretched thin, and they’re often forced to limit their investigations and move on to the next audit as quickly as they can.

Without enough staff, the IRS has slashed even basic functions. It has drastically pulled back from pursuing people who don’t bother filing their tax returns. New investigations of “nonfilers,” as they’re called, dropped from 2.4 million in 2011 to 362,000 last year. According to the inspector general for the IRS, the reduction results in at least $3 billion in lost revenue each year. Meanwhile, collections from people who do file but don’t pay have plummeted. Tax obligations expire after 10 years if the IRS doesn’t pursue them. Such expirations were relatively infrequent before the budget cuts began. In 2010, $482 million in tax debts lapsed. By 2017, according to internal IRS collection reports, that figure had risen to $8.3 billion, 17 times as much as in 2010. The IRS’s ability to investigate criminals has atrophied as well.

Corporations and the wealthy are the biggest beneficiaries of the IRS’s decay. Most Americans’ interaction with the IRS is largely automated. But it takes specialized, well-trained personnel to audit a business or a billionaire or to unravel a tax scheme—and those employees are leaving in droves and taking their expertise with them. For the country’s largest corporations, the danger of being hit with a billion-dollar tax bill has greatly diminished. For the rich, who research shows evade taxes the most, the IRS has become less and less of a force to be feared.