The Internal Revenue Service isn’t easy to love. Politicians from Senator Ted Cruz (R-TX) to former senator Richard Lugar (R-IN) have called for abolishing it, and a House bill to do just that currently has 29 Republican co-sponsors.

And yet the IRS plays a vital function in our country. The taxman not only brings in a huge amount of net revenue; he can also ensure that the wealthiest are paying their share.

Despite this, the agency’s budget has fallen by $2 billion since 2010, even as the IRS took on additional work administering the tax portions of the Affordable Care Act and overseeing the rollout of the 2017 Republican tax cut. After reaching a zenith of $14 billion in 2010, the IRS’s budget has been steadily whittled down; it absorbed $900 million in cuts between 2010 and 2014 alone.

This has left the agency enfeebled. Last year, it had fewer than 10,000 auditors to oversee the entire country’s tax collections—a third less than in 2010. The last time it had such paltry staffing was back in 1953, when both the economy and the population were far smaller.

This means the IRS is doing less to make sure that people pay the taxes they owe. From 2010 to 2017, the number of audits dropped by 675,000—a 42 percent decline. New investigations of people who simply don’t file their taxes fell from 2.4 million in 2011 to 362,000 in 2017. The IRS has also dropped the ball on making sure that people pay up when they’re caught underreporting: These debts expire after 10 years, and the amount that’s expired stood at $8.3 billion in 2017—17 times as much as in 2010.

Reducing or eliminating the IRS is the equivalent of cutting off the country’s nose to spite its face. Americans may chafe at paying taxes, but investing in the IRS generates enormous benefits. Every dollar spent on its enforcement and modernization saves $200 for the government. But if the IRS can’t do its job, that money is left on the table. Revenue from audits has fallen by about $10 billion since 2010.

According to ProPublica, which analyzed data from the IRS and other sources, if the agency were pursuing enforcement as aggressively as it did before 2010, it would have collected $18 billion more in 2017 than it actually did. Since 2011, it’s forgone about $95 billion.

Moreover, all that uncollected money typically sits with those who need it least. The richer someone is, the more likely they are to have misreported their income. And yet audits for the top 1 percent have fallen, from 8 percent in 2011 to just 2.5 percent in 2017, according to ProPublica’s analysis. Audits of millionaires recouped only $1.9 billion in 2018, compared with $5.1 billion in 2010. That almost certainly means that many very wealthy Americans are unfairly holding on to more of their wealth.

You might think that reversing course and cracking down on the well-to-do would be a priority for the IRS. But Republicans have pressured the agency to do the opposite and instead pursue fraud regarding the earned-income tax credit, which is claimed by those earning less than $55,000 a year. EITC audits accounted for more than a third of all audits in 2017. These low-income filers face audit rates surpassed only by those for the country’s millionaires.

Our tax system used to mitigate income inequality through higher taxes on the rich. But for that to work again, we can’t just have higher rates on paper. Someone has to make sure that the rich actually pay what they owe.

There is hope for the agency: After calling for cuts to the IRS in 2018, President Trump released a 2020 budget that proposes $11.5 billion in base funding, as well as an additional $15 billion invested in the agency’s enforcement efforts. The budget estimates that spending this money would generate $47 billion in additional revenue over a decade.

But such budget documents are essentially wish lists that rarely become policy, and Trump’s proposal has so far elicited a tepid response from Republicans. While Congress continues to let the IRS languish, the rich get away with shirking their tax debt, thereby reducing government revenues and exacerbating the pernicious inequality that afflicts our society.