Social Security disability (DI) trust fund

How it's calculated. Par value of Treasury securities held by the fund(s) at month-end 2026-09-30. Ticks at the 12-month trend; a falling number means the fund is being drawn down.

Source. Treasury, Federal Investments Program: Principal Outstanding, official as of Sep 30, 2026.

* Per person (projected population) divides by the US population projected to now: the official Census Vintage 2025 estimate for July 1, 2025 (341,784,857), projected forward at Census's stated growth rate (343,051,422 at build time). Per tax return filed divides by 162,754,810 individual income tax returns filed in FY2025 (IRS Data Book, Table 1-2); a joint return counts once and returns with zero tax liability are included.