This week in Bidenomics: Biden’s best revenue idea

President Biden needs a lot of new government revenue to pay for green energy and social welfare programs he’s urging Congress to pass. Big fights over raising taxes on businesses and the wealthy are underway.

But Biden is also looking for money in a place that shouldn’t be controversial: the bulging pockets of people who already owe billions in taxes, but don’t pay.

There’s long been a “tax gap”—money taxpayers owe that the Internal Revenue Service fails to collect. Much of that tax evasion is deliberate, with money hidden in complex tax shelters the IRS has trouble finding. That makes it hard to know how big the tax gap is, since the IRS can’t count money it can’t find.

But new evidence suggests there’s a shocking amount of money that mostly wealthy Americans owe but don’t pay. On May 20, the Treasury Department published an analysis of the problem estimating the tax gap is nearly $600 billion per year. That might be a conservative estimate. IRS Commissioner Charles Rettig told Congress earlier this year unpaid taxes could total $1 trillion per year.

[Read more: Treasury calls for doubling IRS staff to target tax evasion, crypto transfers]

Whatever the number, it’s a vast sum. Biden’s plan to raise the corporate tax rate from 21% to 28% would only raise $110 billion per year, barely one-sixth the Treasury estimate of the annual tax gap. Biden’s plan to raise income taxes on the wealthy would generate just $75 billion per year. If Congress passed every tax hike Biden is asking for, it would only produce about $210 billion in new revenue per year. Closing the tax gap by half would provide all the funding Biden is looking for, and then some, without any new tax hikes.

This photo taken March 2, 2013, shows the Internal Revenue Service building at the Federal Triangle complex in Washington, Saturday, March 2, 2013. According to projections by the Tax Policy Center, a research organization based in Washington, wealthy families are paying some of their biggest federal tax bills in decades, even as the rest of the population continues to pay at historically low rates. And a new analysis by the Congressional Budget Office shows that average tax bills for high-income families have rarely been higher since the Congressional Budget Office began tracking the data in 1979, while middle- and low-income families aren't paying as much as they used to. (AP Photo/ roomManuel Balce Ceneta)
(AP Photo/ Manuel Balce Ceneta) · ASSOCIATED PRESS

This week’s Treasury report outlines how Biden plans to narrow the tax gap and force evaders to pay. Republicans who have controlled one or both houses of Congress for most of the last 10 years have whittled down the IRS budget and eviscerated its ability to pursue the most aggressive tax cheats. Biden would reverse that trend by providing $80 billion in new IRS funding during the next decade. That would nearly double its annual budget of about $12 billion.

The money would upgrade an antiquated computer system that runs on obsolete programming language. That would enable the IRS to use machine learning and artificial intelligence to better track sophisticated tax cheats. It would also hire and train new auditors, boosting audit rates that have plunged during the last decade. Beefing up tax enforcement would take time, but start to make a big difference by the end of the 2020s.