Now that they’ve started to tackle taxes, it’s time for the Republicans to fix this as well:

As any student of political behavior might have predicted, both parties have learned to game these systems. Obamacare and the tax bill provide many examples.

Democrats got the CBO to count the revenue generated by Obamacare’s Community Living Assistance Services and Supports, or CLASS, Act taxes, fully aware that program’s postponed and unsustainable costs would never be incurred. Republicans likewise took some $300 billion of savings, suddenly available when CBO revised its clearly mistaken estimates of costs of repealing Obamacare’s individual mandate, to pay for tax cuts it couldn’t otherwise get.

This is not a criticism of CBO, which has remained properly nonpartisan and which was designed to estimate revenue flows, not personal choices — such as how many young people would rather pay small individual mandate penalties rather than expensive Obamacare health insurance premiums.

It’s a criticism of the notion that you can create neutral rules that will guide elected politicians to desired results. Politicians and the voters they represent have policy goals they believe important and they have their own ways — fallible, but subject to criticism and debate — to estimate the likely effects of particular policies.

My observation over the years is that systems intended to be failsafe are sure to fail. Forty years of the Budget Control Act regime and 30 years of the opaque Byrd Rule (which allows some Senate measures to pass with 50 votes while others require 60) have shown that both parties have figured out how to game the rules enough to foil those the intended purposes.

The notion that anyone, let alone the CBO, can with any accuracy predict the effects of changes in tax rates and other incentives over a decade is absurd.