You makethe budget

Starting amounts come from the Congressional Budget Office's February 2026 baseline, adjusted for its August 2026 tariff update. Costings are orders of magnitude, per year; those marked “tool estimate” are simple calculations, to be checked.

The measures are chosen to cover, for each item, the range of possible choices, from large savings to large increases, or from tax cuts to tax increases. They are not meant to represent parties. They all come from proposals actually costed by public institutions (Congressional Budget Office, Joint Committee on Taxation…), lawmakers from both parties, think tanks and research centers. When a costing comes from a party or an organization, the source simply says so: you choose a measure for what it does, not for who proposes it.

• Horizon. The deficit and the debt are calculated for fiscal year 2036, the end of CBO's 10-year window, moving forward year by year from the 2027 budget. With no new measures, the deficit excluding interest follows CBO's baseline: only interest and laws already passed make it change.
• Growth and inflation. GDP grows according to the chosen assumption, inflation included. Taxes and spending follow that movement: results are therefore shown as a % of GDP.
• Interest on the debt. Each year, the Treasury replaces old borrowing at about 3.4% on average with new borrowing at about 4.2%. Any reduction in the debt saves interest. Rates: CBO projections.
• Laws already passed. Provisions scheduled to expire under current law expire as planned, as in CBO's baseline: for example the 2025 deductions for tips, overtime, seniors and car loans end after 2028.
• Timing. A measure has half its effect in 2028, then its full effect. Defense, Social Security and some reforms phase in over four years.
• Effects on the economy. When the government spends less or taxes more, the economy slows a little and part of the effort is lost again: about 40 to 45% for spending, 10 to 35% for taxes. The reverse holds when spending more. The lost share is larger for spending and payroll taxes, which are almost entirely spent in the economy, and smaller for taxes paid mostly by the wealthiest, who save part of their income. The slowdown also reduces GDP (by about half of the effort), which weighs a little on the debt ratio. These orders of magnitude follow a Keynesian approach: public spending weighs more on activity than a tax of the same amount. Other schools of economics believe spending cuts slow activity less than tax increases; with their assumptions, savings would look more effective.
• Choice of measures. A measure is included if it is backed by members of Congress, an administration, a public institution or a recognized think tank, and if its cost has been estimated publicly. Warnings follow the same rule for every measure: a warning in case of conflict with the Constitution or a treaty, or a costing very far from independent estimates; a caveat when the yield is very uncertain.
• Incompatible measures. Some measures rule out others (two different ways to reform the same tax): the tool never adds them up.

Detailed method, formulas and limits →

Main sources: CBO budget outlook · CBO options for reducing the deficit · CBO tariff update · Joint Committee on Taxation, Penn Wharton Budget Model, Tax Foundation, Committee for a Responsible Federal Budget (detailed sources on each measure).