Last year, President Biden and congressional Democrats enacted $80 billion in new IRS funding for the next decade. During the debt limit debate earlier this year, Republicans successfully negotiated a $20 billion cut in that funding. And now, in the appropriations showdown, they're going after the rest of it.

The IRS has long been an easy and popular target, because few of us enjoy paying taxes. And the agency has invited criticism with its history of overzealous audits, including a heavy-handed targeting of conservative nonprofit organizations during the Obama administration that fueled the latest round of GOP cuts.

However, defunding and weakening the IRS is not conservative. To the contrary, it will ultimately drive up deficits and raise middle-class taxes.

Between 2010 and 2021, the inflation-adjusted IRS budget fell by nearly one-quarter, according to the Center on Budget and Policy Priorities. Tax enforcement staff declined by 31 percent, and the number of revenue agents collapsed to 1954 levels – even as the taxpaying population doubled, and the tax code grew vastly more complex. Thus, during the 2010s, audit rates fell by 54 percent for large corporations and 71 percent for millionaires.

Consequently, the amount of unpaid taxes has jumped to $625 billion per year, driven heavily by the underreporting of corporate and pass-through business income. Unpaid personal income taxes are vastly concentrated among the highest-earning 5 percent of taxpayers, although errors involving credits such as the Earned Income Tax Credit also cost $42 billion annually.

Nevertheless, House Republicans recently proposed "paying for" emergency aid to Israel with IRS cuts. When the Congressional Budget Office showed that the bill's $14 billion in IRS rescissions would reduce tax collections by $26 billion – offsetting none of the Israel funding – House Speaker Mike Johnson (R-La.) dismissively responded that "only in Washington when you cut spending do they call it an increase in the deficit."

Yet defunding the IRS costs the government money because each dollar in tax enforcement spending brings in as much as $5 to $9 in unpaid taxes (particularly if focused on high earners). Populist pandering aside, lawmakers understand that collecting money requires staff and salaries – you don't see their political campaigns forgoing fundraising staff to save money. The original $80 billion in new IRS funding – to be split between taxpayer services, operations, modernization and tax enforcement focused on upper-income taxpayers – was projected to bring in $180 billion over the decade.

We need this revenue. My fellow fiscal conservatives must grasp the inescapable truth that in the long-term, federal taxes are headed upward. Annual budget deficits now exceed $2 trillion and will surpass $3 trillion within a decade, due overwhelmingly to soaring Social Security and Medicare shortfalls that neither party is willing to touch, and to rising interest rates on the federal debt. Even the most aggressive GOP cuts to discretionary spending would merely trim the projected deficit a decade from now from $3.3 trillion to $3.0 trillion.

So unless lawmakers are willing to finally address Social Security and Medicare, the only remaining debate is over whose taxes will rise and by how much. Simply enforcing existing tax laws is the lowest-hanging fruit – and protecting millionaires from IRS audits (sacrificing trillions of dollars in potential tax revenue over the long term) is a luxury that middle-class taxpayers can no longer afford. Every $100 billion in tax-enforcement collections means $750 per household less in across-the-board tax increases needed to meet the same federal tax revenue target.

More funding can also improve taxpayer services, as roughly 80 percent of taxpayer phone calls to the IRS go unanswered, and the agency faces a mail backlog of 31 million returns. When the agency receives paper returns, employees often must manually enter them into the IRS computers – line by line. And if a number is entered incorrectly, the return processing is delayed until 1970s-era computer programs can identify and fix the error.

Moreover, conservatives should support a functional IRS as a matter of fairness and the rule of law. If our employers can easily hire accountants to evade taxes, our neighbors can collect extra child-tax-credit payments, and our contractors can work fully off-the-books, then the rest of us might feel like chumps.

Lawmakers can also reduce the tax gap by cleaning up the tax code. Though the oft-mentioned flat tax would not fix income underreporting, the code's complexity contributes to tax errors and abuse. Specifically, the IRS is now tasked with implementing social policy through a growing number of refundable tax credits that could be designed as spending programs. The pandemic also required the IRS to implement pandemic relief policies.

Ultimately, winning over GOP appropriators requires addressing the IRS's long history of overreach and targeting of conservative organizations. While the national taxpayer advocate is supposed to represent taxpayers dealing with the IRS, being appointed by the treasury secretary might limit his or her independence. One option would be allowing congressional Republicans and Democrats to appoint their own independent auditors to embed in the IRS with full investigative authority.