Tax enforcement by the Internal Revenue Service has reportedly tumbled to the lowest level in at least four decades.

Just 0.45% of individuals were audited in 2019, down from 0.59% in 2018 and marking the eighth straight year of decline, following years of budget cuts, the Wall Street Journal recently reported.

That figure is down more than half from when the IRS audited 1.1% of tax returns in 2010.

In other words, roughly 1 out of every 220 taxpayers were audited last year. A decade ago, those odds were closer to 1 in 90, CNBC explained.

An IRS report issued this week doesn’t break down audits by income category or provide details about how much revenue they generate, the Journal explained.

As a result, the Treasury is letting billions of dollars annually go uncollected, even as budget deficits rise, tax experts told the WSJ.

“The audit rate reported for 2019 was less than half of what it was in 2010, underscoring the depleted state of the IRS enforcement function, which urgently needs to be rebuilt,” said Chuck Marr, director of federal tax policy at the Center on Budget and Policy Priorities, a progressive group in Washington.

Charles Rettig, the IRS commissioner appointed by President Trump, has been trying to implement a new strategic plan for the agency and has said it remains aggressive in finding people who aren’t following the law, WSJ.com explained.

“Our compliance employees have a commitment to fraud awareness as we continue our enforcement efforts in the offshore and other more traditional compliance-challenged arenas,” Rettig wrote in Monday’s report. “We want to maintain a visible, robust enforcement presence as we continue to explore innovative strategies and techniques in support of our mission.”

However, the average taxpayer has little reason to worry that Uncle Sam will probe your books anytime soon.

“Very few people get audited,” Steve Rosenthal, a senior fellow at the Urban-Brookings Tax Policy Center, told CNBC.

Meanwhile, wealthy Americans are much more likely to be audited than low- and middle-income taxpayers, CNBC explained. "For example, the IRS audited 0.54% of tax returns in 2018 for individuals with an adjusted gross income between $50,000 and $75,000. However, it examined 6.66% of returns filed by those with income over $10 million, according to agency data," CNBC explained.

Last month, the agency said there was a 91.2% conviction rate for tax criminal cases in 2019 in a figure IRS officials vow to improve in coming years as the agency pursues an aggressive enforcement strategy, Bloomberg reported.

The annual report of the IRS’s criminal investigations, released on Thursday, come as the agency is putting a heavy emphasis on enforcement and highlighting its image as a serious law enforcement agency as criminals have found new methods and technologies to evade tax laws.