Transparency is central to our work at the Congressional Budget Office. It deepens understanding of our analyses, builds trust in the agency, and reinforces our credibility.
Created by the Congressional Budget Act of 1974 to offer an alternative to information supplied by the Office of Management and Budget, CBO provides Congress with objective, nonpartisan analysis to support the federal budget process. By law, CBO's chief responsibility is to assist the House and Senate Budget Committees. The Budget Act also gives priority for assistance to the House and Senate Appropriations, House Ways and Means, and Senate Finance Committees. In addition, the agency works closely with Congressional leadership.
CBO fulfills thousands of requests for technical assistance to Members of Congress and their staff each year. At the same time, the Budget Act sets requirements for certain analyses and major products—such as cost estimates and the agency's baseline budget and economic projections—that guide much of our work.
To promote transparency, CBO publishes an annual report on that topic, explains our analytical methods, releases underlying and supplementary data, posts computer code and documentation associated with our models, evaluates the accuracy of our past work, and communicates frequently with Members and Congressional staff, among other activities.
Transparency is also an aspect of our work that we continually strive to improve—and one about which we often receive questions. Below, I address some of the most common questions about CBO's approach to transparency.
1. What informs a cost estimate?
CBO's analysts generally begin by reviewing the proposed legislation—examining how it would change current law and whether its provisions would affect the federal budget. In doing so, they may consult with the bill's authors or sponsors, Congressional staff, federal agencies, and outside experts in academia or other fields, among others.
Second, analysts research the bill's potential effects, gleaning as much information as possible from a wide variety of sources and experts. They then quantify the legislation's likely effects on federal spending and revenues, as well as the costs of any mandates imposed on state, local, or tribal governments and the private sector. (See questions 7, 8, and 9 for a discussion of the types of data and models that CBO uses in its work.) Finally, the analysts present the results and explain the reasoning behind the estimate to ensure transparency.
To provide further information (and transparency), CBO published a primer on how its cost estimates are prepared.
2. How does the agency explain its analytical methods?
CBO regularly publishes reports and supporting documents explaining its analyses, including the agency's general analytical approach and how those methods are applied to specific issues. And most cost estimates include a section describing the basis of the estimate.
In June 2025, for example, CBO published "Dynamic Analysis of Changes to the Supplemental Nutrition Assistance Program (SNAP) in H.R. 1," a slide deck that both reviews the agency's general approach to dynamic analysis and applies it to proposed changes to the Supplemental Nutrition Assistance Program (SNAP). The slide deck provides estimates of the changes' macroeconomic effects and how those effects would further alter the budget. More examples of how CBO explains its analytical methods can be found on the agency's Transparency page.
CBO's staff also frequently brief Members of Congress, their staff, and outside organizations to explain the agency's work, answer questions, and gather feedback. (See questions 8 and 9 to learn more about CBO's models and other tools.)
3. How does CBO evaluate the accuracy of its work?
CBO regularly releases reports comparing its projections with actual outcomes, including a review of the accuracy of projected outlays and revenues for the previous year, as well as periodic reviews of the accuracy of its projections of revenues, outlays, and deficits and debt over time. The agency also evaluates the quality of its economic forecasts by comparing them with the economy's actual performance and with projections from the Administration, private-sector forecasters, the Federal Reserve, and some external groups.
This past September, CBO published a slide deck analyzing the accuracy of the agency's April 2018 revenue projections—the first projections to fully reflect the anticipated effects of the 2017 tax act—explaining why, from 2018 to 2024, those projections and actual outcomes differed.
When enough data become available, CBO evaluates the accuracy of its cost estimates as well. For example, in December 2017, the agency published a report that reviews projections made in March 2010 and May 2013 by CBO and the staff of the Joint Committee on Taxation about key components of the Affordable Care Act, comparing those projections with actual outcomes.
4. How does CBO convey the uncertainty of its estimates?
CBO's budget and economic estimates are designed to fall in the middle of a range of likely outcomes—and the agency describes that range when it publishes those estimates. CBO highlights key sources of uncertainty in its reports so policymakers understand what factors might cause projections to differ from actual outcomes over time.
To further increase transparency, the agency often explains how alternative assumptions about future policies would affect the budget. For example, CBO regularly describes the budgetary effects of some alternative policy assumptions over 10-year and 30-year horizons.
Cost estimates come with their own uncertainties, driven by factors such as broad legislative language, limited data, or gaps in research. CBO explains those sources of uncertainty when they are significant.
The agency also incorporates the effects of administrative and judicial actions into its baseline budget and economic projections and cost estimates. Those actions are often particularly uncertain, and CBO has adopted procedures to address that uncertainty as consistently as possible.
5. When does CBO consult with outside experts?
CBO frequently engages with outside experts to explain its analysis and gather feedback. The agency remains solely responsible for the accuracy of its work, however.
CBO regularly convenes two formal advisory panels—one on health and one on the economy. Panel members represent a broad mix of perspectives from academia, the private sector, and government. The advisory panels meet periodically, and CBO consults with them between meetings as well. Their expertise helps ensure that CBO's economic forecasts and health analyses reflect the latest research and a wide range of views.
When producing particular reports or analysis, the agency frequently consults with other outside experts about specific topics and programs.
6. How does the agency ensure that its work remains objective and nonpartisan?
CBO's reputation, credibility, and usefulness to Congress depend on its being—and being perceived to be—an objective organization free from political bias and involvement.
The agency hires analysts without regard to political affiliation, selecting the most qualified candidates on the basis of their ability to conduct objective, nonpartisan analysis. CBO's policies on hiring and political activity are designed to preserve the agency's nonpartisan standing and the objectivity of our work. The policies delineate strict rules that prevent employees from having financial conflicts of interest and that limit their political activities.
All of CBO's publications are subject to rigorous review to ensure that our analysis is objective and nonpartisan.
7. What types of data does CBO rely on?
CBO uses data acquired from a wide variety of sources, including federal agencies, state and local governments, and private organizations.
The Budget Act gives CBO broad authority to access data, which the agency supplements through specific agreements and collaborations with federal agencies. CBO relies on both public and restricted information: public data support timely responses to Congress, and restricted data—confidential, proprietary, or otherwise sensitive information—provide the details needed for deeper analysis. All data are safeguarded under strict federal standards. A September 2025 report further explains CBO's agreements to access data.
Commonly used public data include unemployment rates and price indicators from the Bureau of Labor Statistics, national accounts from the Bureau of Economic Analysis, and data about business activity from the Census Bureau.
8. How does CBO make its models available to the public?
CBO develops, uses, and continually works to refine a variety of models that vary in complexity, from spreadsheet calculations to large-scale simulation models. When practicable, the agency posts data, computer code, and documentation associated with its models on CBO's GitHub page. (See question 9 to learn more about CBO's easy-to-use modeling tools.)
One example available on GitHub is CBO's capital tax model, called CapTax, which is used to estimate the effects that federal taxes have on the incentives to invest in capital.
In other cases, the agency provides an overview of its models in supplementary materials, such as it did for its life-cycle growth model (also called an overlapping-generations, or OLG, model), which CBO uses to estimate the long-term effects of changes in fiscal policy.
When preparing its estimates, CBO often augments its models with the most up-to-date information from experts and other sources to incorporate the full scope of a legislative proposal's potential effects.
CBO continually assesses opportunities for posting computer code and creating new modeling tools as part of the agency's ongoing efforts to promote transparency—all while following strict federal standards to ensure that sensitive information is not released.
9. How does the agency use modeling tools and infographics in its work?
CBO produces several modeling tools for exploring legislative and policy scenarios. The tools rely on data from the agency's models and are designed for use by a broad audience. They include a "waterfall" model for projecting discretionary spending, a calculator for tabulating debt-service costs, and a workbook allowing users to define and analyze alternative economic scenarios.
The agency also creates infographics—such as its "Atlas of Military Compensation, 2024"—that visually summarize large amounts of data derived from its models and other sources.
10. How does CBO share its work?
CBO releases information in ways that make its analyses widely available, and the agency keeps Congress informed about its completed and forthcoming work.
CBO publicly releases all its cost estimates and analytical reports. It delivers its work to interested Members of Congress and their staff, including the sponsor of legislation or requester of a report, the Chair and Ranking Member of the committees of jurisdiction, and the Budget Committees.
Soon after delivering the work to those key parties, the agency posts it on its website. In addition, when the agency publishes its work, subscribers are notified via an email service; announcements on X (formerly Twitter), Threads, and LinkedIn; and an RSS feed (all accessible from the "Stay Connected" footer on the pages of CBO's website). CBO's cost estimates can also be accessed through the Congress.gov website on pages for specific bills.
Phillip L. Swagel is CBO's Director.