I think Jonathan Chait is vastly overstating the effect of the changes House Republicans are trying to make to how the Congressional Budget Office and Joint Committee on Taxation estimate the effects of legislation.

Congress voted yesterday to require the CBO’s measurement of the budgetary cost of legislation to incorporate assumptions about how it will affect economic growth. Specifically, the GOP’s assumptions. . . .
“Dynamic scoring” allows the Republican majority to impose its own ideological terms on the process of scoring legislation. Many credible economic forecasters would argue that debt-financed tax cuts actually reduce economic growth, and thereby cost the government more, not less, than their static cost. . . .
The new, “dynamic” CBO will be systematically biased to make conservative proposals appear misleadingly cheap and liberal proposals misleadingly costly to the public fisc. . . .
It is possible the Republicanized CBO continues to function in some distorted form, advancing Republican legislative goals by passing off slanted analysis as impartial. Or it is possible it simply loses all of its previous credibility and mutates into another partisan mouthpiece.

As far as I know, the House legislation tracks this description. It does not require any particular methodology. The JCT could, consistent with the legislation, find exactly what Chait’s “credible economic forecasters” do: that tax cuts reduce growth by increasing the deficit. If that happens, I suspect Chait would find that the universe of possibilities for the CBO’s (and JCT’s) future has expanded beyond the two he mentions.