CBO makes a considerable effort to explain the basis of its findings so that Members of Congress, their staffs, and outside analysts can understand the results and question the methodologies used. To begin with, the agency makes its formal cost estimates and analytic reports available on its website to all Members of Congress, their staffs, and the public. The cost estimates include descriptions of the basis for the estimates. And many of the reports provide substantial discussions of the relevant research literature and CBO's modeling approaches—in the text, in separate boxes, or in appendixes. Some examples of reports that provide such discussions are the following:

CBO also publishes data and other technical information with some of its key reports. Some examples are the extensive spreadsheets released with the agency's thrice-annual budget projections and with the Long-Term Budget Outlook, as well as with a report on the fair-value cost of federal credit programs.

To provide details about its analyses for nonexperts and technical descriptions for experts, CBO releases background reports and working papers. The following are some examples:

CBO's transparency also applies to its past work. When the agency updates its baseline budget projections, it explains why those projections have changed. It releases regular analyses of the accuracy of its economic forecasts and has examined the accuracy of its revenue forecasts. And when it revises its view of key aspects of its analyses, it explains the rationale for those revisions. For instance, when CBO revised its view of the effectiveness of malpractice reform in reducing health care costs, of the effect of prescription drug use on Medicare's spending for other health care services, and of the effect on the budget deficit of raising Medicare's age of eligibility to 67, it issued reports explaining why.

In addition, CBO undertakes and publishes analyses of the sensitivity of its estimates to key parameters. For example, CBO's analyses of the economic effects of fiscal policies include alternative estimates that would apply if various effects were stronger or weaker than expected—such as the amount of short-term stimulus provided by lower taxes or higher government spending; the response of the labor supply to changes in tax rates; the effects of budget deficits on private saving and international capital flows; and the effect of changes in federal investment on the economy. Similarly, a report on employment-based health insurance under the Affordable Care Act showed how the results would vary if employers' and employees' responses to that act differed from the agency's expectations.

The agency formally responds to questions from Members of Congress about the methodology used in its analyses. For instance, CBO has explained how it assesses the budgetary effects of possible federal actions to open more federal lands to oil and gas leasing, establish long-term agreements to purchase electric power, and reduce fraud in federal health care programs. CBO's analysts also spend a great deal of time meeting with interested Members of Congress and their staffs to explain the details underlying cost estimates and reports. Finally, to encourage input from outside experts, CBO's employees present information about the agency's analyses, methodology, and results at academic and professional conferences.

Nevertheless, there are limits to CBO's ability to make its analysis transparent. Much of that analysis is very technical, so explaining the models and other analytic techniques used is time-consuming. Because the pace of Congressional action often requires CBO to produce its analysis quickly, the amount of explanation that can be provided when an estimate or analytic report is released is usually limited by the time available. And because the overall demand for CBO's work is high and its resources are constrained, the agency needs to balance requests to explain more about finished analyses with requests for new analyses and with its other responsibilities, such as regularly updating its baseline budget and economic projections.