WELL, GOOD: Trump Says ‘No Change’ to 401(k) Plans Under Forthcoming Tax Proposal.

“There will be NO change to your 401(k),” the president wrote on Twitter. “This has always been a great and popular middle class tax break that works, and it stays!”

Mr. Trump’s comments point to a challenge Republicans face as they race to write and pass a tax plan: They have ambitious targets for rate cuts and a self-imposed $1.5 trillion limit on the size of the tax cut over the decade.

Those guidelines press them to look for large tax breaks they can limit or repeal and to seek budgetary maneuvers that shift the timing of tax revenue into the period measured by congressional scorekeepers. The proposal to cap 401(k) contributions at as little as $2,400 a year and push additional savings into so-called Roth-style accounts where posttax dollars go in and money comes out tax-free in retirement was a combination of both. Much of the revenue it generated would have come from accelerating tax collections from the future into the near term.

Today’s revenue schemes don’t matter in the long term, because Washington will never collect enough in revenue to pay for the entitlement explosion. We can fiddle around the tax margins all we like, but until Congress tackles our spending addiction, it won’t amount to much.