What are independent forecasts for U.S. debt-to-GDP through 2035 under current policy assumptions?

1. The CBO baseline: the commonly cited midline

The Congressional Budget Office’s ten‑year Budget and Economic Outlook projects federal debt held by the public climbing to about 118 percent of GDP in 2035, with deficits roughly $1.9 trillion this year and rising pressures from mandatory spending and net interest pushing the adjusted deficit to about 6.1 percent of GDP by 2035 ^{[1] [5] [3]}.

2. What non‑government forecasters are saying

Independent fiscal groups and think tanks using “current policy” baselines generally map close to the CBO but with important differences: the Committee for a Responsible Federal Budget’s adjusted August 2025 baseline expects debt around 120 percent of GDP by 2035 (and 107 percent by 2028) and estimates roughly $1 trillion more in cumulative deficits than CBO over the decade ^{[2] [6]}, while the American Action Forum’s estimate puts the ratio near 119 percent by FY2035 ^[4]; the Peter G. Peterson Foundation and related trackers echo CBO’s ~118–118.5 percent figure ^[3].

3. Scenarios that drive debt well above the baseline

Those modest differences mask larger upside risk: CRFB’s “alternative” scenario—assuming temporary tax and spending measures are made permanent, tariffs prove temporary or illegal, and long‑term yields stay elevated—produces debt of as much as 134 percent of GDP by 2035; other analysts show ranges into the mid‑130s under sustained higher interest rates or permanent policy changes ^{[6] [2]}. These alternative pathways are not CBO law‑baseline forecasts but illustrate how small shifts in revenues, interest rates, or temporary provisions can add many percentage points of GDP to the ratio ^{[2] [6]}.

4. The mechanics: deficits, aging, and interest

Most forecasters point to three common drivers: persistent primary deficits from growing Social Security and Medicare outlays tied to demographic trends, interest costs that rise as the stock of debt grows, and revenue assumptions (including whether tax provisions expire and whether new tariff receipts persist), with net interest projected to rise from about $1 trillion now toward $1.8 trillion by 2035 in several projections—raising debt service from roughly 3.2 percent of GDP today to over 4 percent by 2035 in some estimates ^{[1] [2] [3] [4]}.

5. Economic implications and contested effects

Analysts quantify potential macro costs of that path: some studies cited by asset managers and fiscal groups suggest debt exceeding 120 percent of GDP can modestly reduce real GDP growth (e.g., 0.25–0.5 percentage points annually in some studies) and shrink investment—findings used to argue for near‑term fiscal adjustment—while policy groups like the Peter G. Peterson Foundation commission models that show cumulative dampening effects on output and wages relative to a stabilized‑debt scenario ^{[7] [8]}. Alternative voices warn models vary on magnitude and that timing, productivity, and global capital flows matter for outcomes; those caveats are visible in the divergence between CBO baselines and high‑debt alternative scenarios ^{[6] [7]}.

6. Bottom line and what “current policy” means for forecasts

Under mainstream independent forecasts using CBO‑style current‑law assumptions, debt held by the public is expected to sit roughly between 118 and 120 percent of GDP by 2035; credible alternative assumptions about permanent policy choices, tariff legality, or sustained higher interest rates can push that figure into the 130s, and rising interest costs and larger deficits are central to those risks ^{[1] [2] [6] [3]}. These projections depend on explicit assumptions—Tax Cuts and Jobs Act expirations, tariff permanence, and interest‑rate paths among them—and different but plausible assumptions change the picture materially, so the range is as important as any single point estimate ^{[5] [2]}.