Republicans have been struggling to do a few things at once with their changes to the tax code: cut taxes for the middle class, knock the corporate rate down to 20 percent (from 35 percent), keep the revenue loss to $1.5 trillion over ten years (as required by their budget resolution), and avoid increasing the budget deficit at all outside a ten-year window (as required by the Senate’s filibuster-proof “reconciliation” process).

They just might have pulled it off, according to estimates the Joint Committee on Taxation released last night of the Senate’s newest plan. It’s not pretty as policy, but it works in terms of process and (maybe) politics.

One major new element is that the individual tax cuts, including those that apply to estates and small-business income, sunset after 2025. Another element is that the child tax credit is boosted to $2,000 (from the current $1,000) to help shield the middle class from tax increases. And another, as I noted yesterday when news of it spread, is that Obamacare’s individual mandate is repealed — which saves the government money in health-care subsidies. The plan loses $1.4 trillion over ten years, but it’s actually $30 billion in the black in the final year, 2027.

A few issues:

‐ In addition to losing all their big breaks after 2025 unless Congress extends them, individuals will see their tax brackets (and other variables) indexed to a less friendly measure of inflation. This will raise $31.5 billion in 2027 alone. If the idea is that Congress will extend the breaks, the expiration date is a budget gimmick and the plan loses more money than announced; if not, people won’t like that the corporate cuts are permanent while the individual cuts are not, especially if individuals will end up paying higher taxes than they would otherwise.

‐ $1.4 trillion is a lot of revenue loss, and since there are no spending cuts to offset it, it’s money we’ll be passing on to our kids as debt. As I spelled out last week, some economists believe government borrowing “crowds out” private investment, which would undermine any economic growth the plan creates. But it doesn’t seem like either house of Congress has any intention of pursuing revenue neutrality.

‐ The plan simply zeroes out the individual-mandate penalty. There doesn’t seem to be any replacement for it. As I said yesterday, this will definitely raise premiums (because healthy people will wait until they get sick to buy insurance) and risks destabilizing the insurance market as well. It will also increase the number of uninsured by eye-popping numbers, though many of these folks would freely opt out of buying a plan when they’re not forced to. Further, it’s not clear the predicted deficit reduction from repealing the mandate will even materialize; the CBO is in the process of revising its methodology and says future estimates will be lower than its previous ones. CBO most recently said $338 billion over ten years; the JCT report assumed $318 billion.