Congressional Democrats need a lot of new tax revenue to pay for at least a portion of the social spending they wish to pass. But they also have a few tax breaks they want to give to their preferred groups.

Among they: labor unions. For union members, Democrats propose a tax deduction of up to $250 for union dues:

The deduction is “above the line,” meaning filers can exclude the cost of dues from their gross income. In other words, union dues would get the same treatment now reserved for things like insurance premiums and retirement contributions. The deduction would last through 2025. The Joint Committee on Taxation estimates its cost at $1.8 billion.

Supporters frame the tax break as relief for workers. “Unions are the backbone of the middle class,” said Democratic Sen. Bob Casey while introducing a similar provision in April. “This legislation would put money back in the pockets of working families.”

Except, as the Wall Street Journal notes, this sop to unions is bad tax policy for the very members the deduction is supposed to help:

It’s also a step backward for the tax code, which Republicans helped to rationalize in 2017. The Tax Cuts and Jobs Act nearly doubled the standard deduction to replace a hodgepodge of tax breaks, including a previous “below the line” deduction for dues. Instead of returning cash to the average worker, Democrats want all workers to subsidize the unionized few—along with their own election campaigns.

The problem, as always, is the cumbersome, confusing, and corrupt tax code. If the goal is to help workers, or families or anyone else politicians might think of, the tax code needs to be simple, fair and broad-based. In other words, junk the current monstrosity, and replace it with a flat tax.