CBO, JCT share methods for analyzing legislative proposals impacting health insurance coverage

The Congressional Budget Office (CBO) and the Joint Committee on Taxation (JCT) revealed in a recent report how they jointly analyze proposed legislation that would impact health insurance coverage for individuals younger than age 65, detailing how they develop analytic strategies, model a proposal’s effect, and finalize their analysis (CBO Report, February 2018).

Analytic strategy development

First, the CBO and JCT put together an analytic strategy. The agencies formally develop their strategy once the proposed legislation’s specifications become available, an official request for analysis has been made, and the CBO and JCT arrange the time to commence the analysis. However, the agencies also often work informally with Congressional staff during development of the proposal. The agencies begin by reviewing the policy specifications. The CBO and JCT consider how the proposed legislation would impact existing law and how the proposed legislation is different from earlier proposal drafts. The agencies work to verify that the Congressional staff’s intent is reflected in the language and then estimate the legislative effect by, namely, identifying how the proposal could affect health insurance coverage and the federal budget.

The CBO and JCT focus on the policy changes most likely to impact health insurance coverage or cost, ranging from the straight-forward to the more complex. Another key aspect the agencies consider is timing and what additional “administrative infrastructure” is necessary to bring about the changes of the proposed legislation—and how long it would take to do so. The timing element includes estimates of how other stakeholders (state governments, insurers, employers, etc.) would respond and how long it would take for them to implement the proposed changes. To help with their estimates, the agencies rely on past cases of legislative reform programs. Further, the agencies seek input from outside experts and existing evidence while maintaining the required confidentiality of a proposal.

Proposal effect modeling

Second, the CBO and JCT undertake modelling the impact of the proposed legislation. Primarily, the agencies rely on CBO’s health insurance simulation model (HISIM), Medicaid enrollment and cost models, and JCT’s individual tax model. These models use data on health insurance coverage information for everyone younger than 65, Medicaid enrollment and expenditures, and detailed tax return information. The agencies also draw estimates based on information HISIM cannot project, namely, the behavior of states, employers, and insurers. These initial projections are incorporated as inputs into HISIM (state, employer, and individual enrollee behavior) or assessed outside HISIM (insurer behavior). CBO and JCT also use HISIM to estimate stakeholder responses to new coverage options. Medicaid enrollment and cost projections use HISIM estimates in addition to a more detailed Medicaid model and other methods. JCT usually provides estimates of proposed tax liability changes using its individual tax model.


Finally, both the CBO and JCT engage in rigorous review of their respective analysis results in order to ensure objectivity and proper analysis. Specifically, they examine results of one or more years out of the 10-year projection period to ensure that the analysis is being computed as intended and compare results against previous analyses. The agencies also inspect for programming errors or unexplained results. The CBO and JCT consider changes to the results if there were different critical inputs. The agencies prepare a formal written estimate and explanation thereof and, before releasing it to Congress and the public, agency staff carefully review the report.