How are provisional income and combined income calculated for Social Security taxation in 2026?
Executive summary
Provisional income (also called combined income) for determining whether Social Security benefits are taxable is calculated as adjusted gross income (AGI) plus tax‑exempt interest plus one‑half of Social Security benefits; the same combined/provisional income figure is used to compare against the statutory thresholds that trigger 50% or 85% taxation of benefits (single: $25,000 and $34,000; married filing jointly: $32,000 and $44,000) [1][2][3]. Multiple mainstream personal‑finance outlets and state research explain that if provisional income falls between the lower and upper threshold up to 50% of benefits may be taxable; above the upper threshold up to 85% may be taxable [4][3].
1. What “provisional” or “combined” income is — the calculation
The calculation is simple and consistent across sources: take your adjusted gross income (or gross income in some explainers), add any tax‑exempt interest (for example municipal bond interest), then add one‑half (50%) of your annual Social Security benefits — the sum is called provisional income or combined income and is the number the IRS uses to decide whether any of your benefits are taxable [1][5][4].
2. How the provisional figure is applied to tax rules in 2026
Once you compute provisional income, compare it to the statutory thresholds. For single filers the key breakpoints are $25,000 and $34,000; for married couples filing jointly they are $32,000 and $44,000. If provisional income is below the lower breakpoint, none of the Social Security benefits are taxed federally; if between breakpoints up to 50% of benefits may be taxable; if above the upper breakpoint up to 85% may be taxable [3][2][6].
3. Examples and worksheet guidance reported by sources
Multiple outlets note the IRS provides Worksheet A in Publication 915 to walk taxpayers through the precise arithmetic and to determine the lesser‑of calculations that set the taxable portion (for example, a single filer with provisional income in the middle band pays taxes on the lesser of 50% of benefits or 50% of the excess over the base amount) [4]. Practical examples in the coverage show how half of Social Security is added to other income to produce provisional income [5][4].
4. Terminology and small but important distinctions
Some writeups use “adjusted gross income” (AGI) as the starting point while others say “gross income”; functionally the widely cited formula used by financial outlets and state research is AGI + tax‑exempt interest + 50% of Social Security benefits — those are the components repeated across sources [1][7][5]. The IRS legal provision itself (IRC §86) does not use the casual term “provisional income,” but taxpayers and advisers do [4].
5. Policy context and why 2026 matters to retirees
Several outlets emphasize that the thresholds are not indexed for inflation, so modest COLAs can push retirees over the breakpoints; commentators warned that the 2026 2.8% COLA could push people past the limits and make benefits taxable even when they previously were not [3][8]. Reporting also notes recent tax changes (an enhanced senior standard deduction in the “One Big Beautiful Bill”) do not repeal the Social Security taxation rules, so retirees may still face partial taxation even with other tax reliefs [6][9].
6. Areas where sources diverge or leave gaps
The mechanics of “lesser‑of” calculations and the way specific deductions interplay with provisional income are described in general terms across sources but detailed numeric examples and step‑by‑step worksheets are available through the IRS (Publication 915) rather than fully reproduced in the cited articles — available sources do not present the full IRS worksheet line‑by‑line here [4]. Also, state variations (which states tax Social Security and how they use the federal exclusion) are discussed by Minnesota House research but state‑by‑state treatment varies and isn’t comprehensively listed in these articles [10].
7. Practical takeaways for taxpayers
Compute: AGI + tax‑exempt interest + 0.5 × Social Security = provisional/combined income [1][5]. Compare to $25k/$34k (single) or $32k/$44k (joint) to see whether 0%, up to 50%, or up to 85% of benefits could be taxed [3][2]. If you’re near the thresholds, consider timing income, reviewing tax‑exempt interest, or consulting the IRS worksheet/financial advisor because modest income or COLA changes may alter taxability [4][6].
Limitations: this summary relies on the tax thresholds and explanations published by the cited personal‑finance outlets and state research; for the exact IRS computations and to file correctly taxpayers should consult IRS Publication 915 and professional tax advice — the sources here summarize but do not reproduce the full IRS worksheet [4][10].