There is no single cost figure for the “Trump tax cuts”: estimates refer either to the 2017 Tax Cuts and Jobs Act (TCJA) or to the broader 2025 law that made most of its expiring individual tax provisions permanent, and they use different periods and budget measures. The original TCJA’s enactment estimate was $1.5 trillion over fiscal years 2018–2027. For the 2025 reconciliation act, the Congressional Budget Office (CBO) estimates a $4.2 trillion increase in deficits over FY2025–FY2034 versus its January 2025 baseline, and its updated outlook attributes a $4.7 trillion increase in projected deficits over 2026–2035 to legislative and economic changes stemming from that law.
How much did the 2017 Trump tax law add to the deficit?
The original TCJA, Public Law 115-97, was estimated to increase deficits by $1.5 trillion over FY2018–FY2027 when enacted in 2017. The figure is the Joint Committee on Taxation’s (JCT) enactment estimate, as summarized by the Congressional Research Service (CRS); it is not a current estimate of the later 2025 law. CRS report.
CBO’s April 2018 projection put the 2017 act’s deficit increase at $1.9 trillion over 2018–2028, including macroeconomic feedback and debt-service costs. CBO said in 2020 that it had not subsequently updated that particular estimate at that time. Its longer period and inclusion of interest and economic effects mean it should not be treated as a directly comparable revision of the $1.5 trillion enactment estimate. CBO response.
What did the 2025 extension cost?
On July 4, 2025, Public Law 119-21 extended most of the 2017 individual tax provisions that had been scheduled to expire after 2025, alongside other budget provisions. CBO’s latest outlook gives several figures for its effects. They differ because they cover different fiscal windows and measures—not because they are competing totals for precisely the same question. CBO, The Budget and Economic Outlook: 2026 to 2036.
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| Estimate | What it measures | Period and comparison |
|---|---|---|
| $3.4 trillion | Increase in primary deficits, excluding debt service and budgetary feedback | FY2025–FY2034, relative to CBO’s January 2025 baseline; CBO/JCT conventional estimate |
| $718 billion | Additional interest associated with that primary-deficit estimate | FY2025–FY2034; before macroeconomic feedback |
| $4.2 trillion | Increase in total deficits, including interest and macroeconomic feedback | FY2025–FY2034, relative to CBO’s January 2025 baseline |
| $4.7 trillion | Increase in projected cumulative deficits attributed to legislative and economic changes stemming from the law | 2026–2035 in CBO’s updated outlook; includes $3.7 trillion in primary-deficit effects and $0.9 trillion in increased debt-service costs |
| $4.9 trillion | Reduction in projected federal revenues | 2026–2035 in CBO’s updated outlook; more than 80 percent arises from permanent extension of most scheduled-to-expire 2017 provisions |
The $4.9 trillion revenue reduction is not the law’s net deficit effect: a revenue change is only one part of the budget picture. Likewise, the $4.7 trillion figure uses the updated outlook’s attribution of legislative and economic changes since its prior baseline, whereas the $4.2 trillion figure compares the law with CBO’s January 2025 baseline over FY2025–FY2034.
Does the cost include interest on the debt?
It depends on the estimate. The $3.4 trillion figure is the conventional primary-deficit estimate and excludes debt-service costs; CBO separately estimated $718 billion in added interest for the same FY2025–FY2034 period. Before macroeconomic feedback, those amounts produce a $4.1 trillion deficit increase. CBO’s $4.2 trillion total-deficit estimate for that period also reflects macroeconomic feedback and associated interest-rate effects. In the 2026–2035 outlook, CBO attributes $0.9 trillion of the $4.7 trillion increase to higher debt-service costs.
Why are there different estimates of the cost?
Before comparing numbers, check what law, baseline, years, and budget measure each one describes. In particular, distinguish the original TCJA from the 2025 law extending many of its provisions.
- Policy scope: An estimate may cover the 2017 law as enacted, selected extensions, all provisions scheduled to expire or become less generous, or the full 2025 reconciliation act.
- Baseline: The counterfactual matters. The 2025 law’s extension of provisions scheduled to expire produces a different comparison from a scenario that assumes those provisions continue.
- Time window: FY2018–FY2027, 2018–2028, FY2025–FY2034, and 2026–2035 are not interchangeable. Cumulative totals also depend on which years are included.
- Budget measure: Revenue loss, primary deficits, total deficits, and interest costs describe different parts of the budget.
- Economic treatment: A conventional score excludes macroeconomic feedback; a projection may include behavioral and broader economic effects as well as debt service.
Earlier extension estimates illustrate the scope issue. In 2024, CBO and JCT estimated that extending all TCJA provisions scheduled to expire or become less generous would cost $4.0 trillion over FY2025–FY2034; this was a pre-enactment scenario, with most effects beginning in FY2026. CRS report.
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A separate 2023 CBO table estimated selected extensions over 2024–2033 using CBO’s May 2023 baseline. The listed pre-interest deficit effects total $2.94 trillion: $2.488 trillion for individual income-tax changes, $126 billion for higher estate and gift tax exemptions, and $325 billion for investment-cost provisions. The table’s associated debt-service costs total $350 billion ($278 billion, $13 billion, and $59 billion, respectively). These selected scenarios exclude macroeconomic feedback and should not be added to the later full-law estimates. CBO alternative-policy report.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Who produces the estimates, and how certain are they?
JCT provides the official estimates for legislation changing federal taxes; CBO incorporates those estimates into its legislative cost estimates and projects broader budget effects. Estimates are projections against specified baselines, not a final observed tally of every downstream effect. CBO says results are uncertain because implementation, state responses, household and business decisions, and economic conditions can differ from assumptions; estimates also change as policies and baselines change. CBO 2026 outlook.
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