The Social Security system’s long-term financial hole just grew by trillions of dollars, driven almost entirely by two demographic forces: Americans are having fewer children, and the trustees now expect fewer immigrants to enter the country over the coming decades. The 2026 Annual Report of the Board of Trustees of the Federal Old-Age and Survivors Insurance and Federal Disability Insurance Trust Funds puts the present-value gap between future income and future costs at negative $30.5 trillion, according to the Office of the Chief Actuary. That figure, which represents the shortfall over a 75-year projection window, lands harder than prior estimates because the trustees slashed both their fertility and net immigration assumptions at the same time.
How lower births and fewer immigrants widened the OASDI gap
Social Security collects payroll taxes from current workers to pay current retirees. When the pool of future workers shrinks, so does the revenue base, while obligations to existing beneficiaries remain locked in. In the trustees’ intermediate scenario, the assumed long-run fertility rate now settles at 1.75 children per woman, a downward revision that reflects years of declining birth rates recorded in CDC National Vital Statistics System data. At the same time, the trustees cut their projections for net immigration, reducing the expected flow of working-age people who would otherwise pay into the system for decades before collecting benefits.
Both changes push in the same direction. Fewer births mean fewer native-born workers entering the labor force in the 2040s and 2050s. Lower immigration means the near-term workforce also grows more slowly than previously assumed. The long-range estimates section of the 2026 report attributes the worsening balance to reduced ultimate fertility and to changes in immigration assumptions, though it does not assign a precise dollar share to each factor separately. The trustees’ summary similarly describes the deterioration as a “large demographic-driven worsening” tied to both forces acting together, with economic factors like productivity and wage growth playing a secondary role in this year’s revisions.
The combined OASDI long-range actuarial deficit, measured as a percentage of taxable payroll, also widened. That metric matters because it translates the abstract present-value shortfall into a concrete policy question: how much would payroll tax rates need to rise, or benefits need to fall, to close the gap over 75 years? A larger deficit as a share of taxable payroll implies either a bigger across-the-board tax increase, deeper benefit reductions, or some combination of the two if lawmakers want to restore long-term balance under current-law benefits formulas.
The trustees’ report also updates the projected depletion dates for the Old-Age and Survivors Insurance (OASI) trust fund and the combined OASDI funds. When a trust fund is “depleted,” incoming payroll taxes still arrive every year, but they are no longer supplemented by interest income or asset redemptions, so benefits would have to be cut to match annual revenues unless Congress intervenes. In the 2026 report, those depletion dates move closer in time, underscoring that demographic deterioration is not just a distant problem but one that tightens the window for legislative action in the 2030s.
Trustees versus CBO: diverging demographic baselines
The Congressional Budget Office publishes its own demographic outlook covering roughly the next three decades, offering an independent set of fertility and immigration projections. Both the trustees and CBO draw on the same underlying birth certificate data from the CDC and immigration statistics from the Department of Homeland Security. Yet they do not model the future identically. The trustees build their 75-year projections using assumptions about how net migration, fertility, and mortality will evolve well beyond the standard budget window, while the CBO outlook uses a shorter horizon and different policy baselines for legal immigration categories.
That structural difference matters. When both agencies cut their immigration assumptions in response to the same real-world trends, such as changes in enforcement or visa issuance, the trustees’ model amplifies the fiscal effect because it carries reduced migration forward over a longer time span. The result is that demographically equivalent adjustments can show up as a larger deterioration in the trustees’ long-range actuarial balance than in CBO’s 30-year projections, even if the near-term population paths look similar.
Fertility assumptions can diverge as well. CBO may project a modest rebound toward replacement levels if economic or policy factors shift, while the trustees, reacting to persistent declines in observed birth rates, may embed a lower “ultimate” fertility level in their long-run scenario. Over 75 years, small differences in the assumed number of children per woman compound into large gaps in the number of future workers, taxpayers, and eventual beneficiaries.
Those modeling choices help explain why the trustees’ 2026 report shows such a sharp worsening in the long-range shortfall when both fertility and immigration are revised downward simultaneously. A lower starting point for births and migration today implies fewer workers in each subsequent decade, and the 75-year window ensures that the lost contributions of those never-born or never-arrived workers are fully tallied. By contrast, a shorter projection horizon would capture only part of that effect.
For policymakers, the key takeaway is not that one projection is “right” and the other “wrong,” but that Social Security’s finances are highly sensitive to demographic assumptions. As the 2026 trustees report makes clear, even modest shifts in expected fertility and immigration can translate into trillions of dollars in additional long-term obligations. That sensitivity raises the stakes for any policy debate over immigration levels, family supports that might influence birth decisions, and broader reforms to how Social Security is financed.
