The White House describes the Build Back Better Act as a way to strengthen “the backbone of the country — the middle class.” Why, then, does the current version of the bill include a massive tax cut for the rich?

The bill devotes nearly $300 billion to increasing the cap on the state and local tax deduction — known as the SALT deduction — from $10,000 to $80,000 through the end of 2025. It goes without saying that if you are paying tens of thousands of dollars in state and local taxes, you probably aren’t middle class. (And people with just over $10,000 of state and local taxes probably are collecting the $25,100 standard deduction rather than itemizing.) Based on a Tax Foundation analysis of a similar plan, roughly 98 percent of this tax cut would go to households making six figures or more.

The SALT cap was put in place by the 2017 tax law to help defray the costs of tax rate cuts — including the cutting of the top individual rate from 39.6 percent to 37 percent As the name suggests, it limits how much you can deduct of what you’ve paid in state and local income taxes, and property taxes, from your federally taxable income. While the vast majority of Americans saw their total taxes go down from the 2017 tax cuts despite this measure, the SALT cap prevented what would have been even larger tax cuts for high-income households.

Now Democrats are proposing a massive increase in that cap, one that would deliver nearly $130,000 over five years to the handful of wealthy taxpayers with enough income to owe $80,000 in state and local taxes annually.

At its current size — negotiations are continuing — this tax cut would be the third largest measure in the bill. Three hundred billion dollars is more than the bill spends on universal preschool, the child tax credit and the earned income tax credit combined. It is also more than the bill allocates for health care for the poor, elderly and disabled. And it’s about as much as would be spent on renewable energy tax credits.

The bill’s architects claim that the measure pays for itself, but that’s a hollow claim. It relies on a budget trick whereby lawmakers extend the $80,000 SALT cap beyond 2025, and lowering it to $10,000 for 2031 only, while letting the remainder of the 2017 tax law expire as scheduled. It’s a good bet lawmakers are going to ultimately extend most of those remaining tax cuts — at least the share going to people making less than $400,000 — turning these revenue increases into revenue losses.

Democrats had originally intended to reverse some of the 2017 tax cuts — by restoring the highest individual rate to 39.6 percent and increasing the corporate tax rate from 21 percent up to as high as 28 percent. Unable to secure 50 votes in the Senate, they abandoned those efforts (although they did retain a surtax on multimillionaires and a higher minimum corporate tax). Now they are moving in precisely the opposite direction — doubling down on tax cuts for the wealthy. The proposal contradicts the stated rationale for the Build Back Better Act, which is to make investments in families paid for by higher taxes on the well-to-do.

Things could be worse, it’s true. Earlier this week, the House appeared ready to fully repeal the SALT cap, cutting taxes for the top 0.1 percent by an average of $150,000 per year. Full SALT cap repeal would have been the largest policy in the bill, dwarfing every other priority and providing a large net tax cut for the wealthy. Sen. Bernie Sanders (I.-Vt.) and others objected, and that idea was withdrawn and replaced. But the current version of SALT relief is still hard to defend.

Its proponents say that SALT cap “relief” is needed for the middle class. But only about 2 percent of the cuts – $6 or $7 billion out of nearly $300 billion – would benefit those making less than $100,000 per year. They say SALT cap “relief” would improve fairness, since people from wealthy “donor states” pay more in federal taxes than those from poorer “moocher states.” But that’s simply how progressive taxation works – the more you make, the more you pay. We’re also told SALT cap “relief” will help states raise taxes to fund important services. But scholars who have studied the issue say there is little evidence that states’ tax policies are affected by the federal deduction. And the fact that we’ve recently seen progressive income tax increases in New York, New Jersey and D.C. should put this claim to bed.

The reality is that the SALT cap represents an improvement to the tax code. It improves tax neutrality and equity between similar taxpayers. (People from New York and Texas who earn the same amount should pay the same in federal taxes.) And it supports simplicity, by shifting many Americans away from itemized deductions and toward the much simpler (and now much larger) standard deduction.

There are ways to make SALT cap changes less costly and less regressive than the current proposals. Sanders, for instance, has proposed repealing the cap for people who make $400,000 or less annually. But these modifications can’t turn a bad policy into a good one. No changes to the cap can deliver more than a $20 tax cut to the average middle-income household, or offer more than a tiny fraction of the tax cut to the bottom three-fifths of Americans.

“Show me your budget, and I’ll tell you what you value.” President Biden often says. Enacting this tax cut into law would speak volumes.