Over time, as Obamacare was implemented, experts began to question the importance of the mandate. But when Republicans sought to repeal and replace Obamacare in 2017, the CBO did not adjust its assumptions about its power. For instance, in one version of the House bill, the CBO found that before any cuts to actual spending went into effect, 14 million fewer people would be insured and that, “Most of the reductions in coverage … would stem from repealing the penalties associated with the individual mandate.” Incredibly, the CBO estimated that 5 million fewer people would enroll in free Medicaid mainly due to the elimination of the penalties. This number accounted for more than half of the 24 million the CBO said the Republican plan would reduce coverage for overall over a decade.

While any CBO analysis of the Republican bills was likely to project large coverage losses due to the cuts to Medicaid and subsidies, if CBO had more realistic assumptions about the mandate, the numbers would have been significantly smaller, and perhaps left more room to convince centrist Republicans to get on board.