Half of it, then 85 percent of it, and the line has not moved since 1993.
Whether a Social Security check is taxed depends on everything else on the return plus half the check, measured against two thresholds that were set decades ago and never indexed. Enter the benefit and the other income to see the taxable share and how close the next threshold is.
Section 86 thresholds, 2026 record · Last reviewed September 5, 2026 · Facts · The table · Methodology
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The total for the year, before Medicare premiums are taken out. It is box 5 of your SSA-1099.
Pensions, IRA withdrawals, wages, interest, dividends, and tax-exempt interest, before any deductions.
The two lines were set in 1983 and 1993 and have never been adjusted for inflation. That is why a tax that reached few retirees then reaches most now. Between the lines, each extra dollar of other income makes 50 cents of benefit taxable. Above the second line, each extra dollar makes 85 cents taxable, until the 85 percent ceiling is reached.
This follows the federal rule for taxing Social Security benefits, using the 2026 figures. It shows how much of the benefit is taxable, not the tax itself, which depends on your deductions and bracket. It does not cover a married person filing separately while living with their spouse, whose benefit is taxable from the first dollar of income. Educational, not advice.
This is a simplified model, not your actual tax return or plan. It only knows what you type in, leaves out rules that may apply to you, and cannot weigh the other facts and trade-offs a real decision depends on. Before you act, talk with a professional who knows your whole situation.
Built by Joshua Mangoubi, CFA, MBA. By using this tool you agree to the tool terms, which include that results vary with each use and over time. Cite this tool, or take a table or chart
How it counts. Section 86 of the Internal Revenue Code applied as written: provisional income against the base and adjusted base amounts, the 50 percent tier, the 85 percent tier, and the ceiling, with the two worked examples in IRS Publication 915 reproduced exactly.
What it assumes. A single or joint return, the whole year's benefit, and other income entered as one figure including tax-exempt interest. It does not touch the deduction side of the return or compute the tax itself; it answers how much of the benefit becomes income.
Where we fit in. We integrate tax considerations into your investment strategy and collaborate with estate attorneys and CPAs to ensure your plan is coordinated. We are not a law firm or accounting firm, so we do not provide legal or tax advice. Everything in this material is for educational purposes, based on primary sources. Before taking any action, please consult the appropriate professionals to apply these ideas to your situation.
The facts, in one place.
Six quotable sentences from section 86 of the Internal Revenue Code.
- Whether a Social Security benefit is taxed depends on provisional income: adjusted gross income without the benefit, plus tax-exempt interest, plus half the benefit.
- Nothing is taxable below a base amount of $25,000 on a single return and $32,000 on a joint return. Up to half is taxable between the base and an adjusted base of $34,000 single and $44,000 joint. Up to 85 percent is taxable above that.
- The thresholds were fixed in 1983 (the base) and 1993 (the adjusted base) and are not indexed to inflation, so each year more retirees cross them without any change in real income.
- A married couple with $36,000 of benefits and $40,000 of other income has provisional income of $58,000; $17,900, 49.7% of the benefit, is taxable.
- Eighty-five percent is the ceiling. No level of income makes more than 85 percent of a benefit taxable.
- Inside the two zones, each extra dollar of other income drags 50 cents, then 85 cents, of benefit into taxable income, so the marginal tax rate on that dollar can be 1.5 or 1.85 times the bracket rate.
The thresholds.
The two thresholds for each filing status and the share of the benefit each zone can tax.
| Zone | Single | Married filing jointly | Share of benefit taxable |
|---|---|---|---|
| Provisional income at or below the base | $25,000 | $32,000 | None |
| Between the base and the adjusted base | $25,000 to $34,000 | $32,000 to $44,000 | Up to 50 percent |
| Above the adjusted base | Over $34,000 | Over $44,000 | Up to 85 percent |
How the rule works.
Section 86 tests provisional income, which is everything on the return except the benefit, plus tax-exempt interest, plus half the benefit. Below the base amount none of the benefit is taxed. Between the base and the adjusted base, the taxable part is the smaller of half the benefit and half the excess over the base. Above the adjusted base, it is the smaller of 85 percent of the benefit and 85 percent of the excess over the adjusted base plus the smaller of the first-tier amount and a fixed cap.
The practical effect is a band of income in which each extra dollar of pension, IRA withdrawal, or interest also pulls part of the benefit into income. Inside the 50 percent zone the marginal rate on that dollar is one and a half times the bracket rate; inside the 85 percent zone, 1.85 times, until the ceiling, after which the benefit's taxable share is fixed and the band is behind you. Withdrawal sequencing and Roth conversions are usually planned around this band.
Methodology.
- Inputs. The year's Social Security benefit (box 5 of the SSA-1099), all other income including tax-exempt interest, and the filing status.
- The formula. Section 86(a) through (c) applied literally, with the base amounts, adjusted base amounts, and second-tier caps from the annual record.
- Validation. Six pinned cases, two of them the worked examples in IRS Publication 915, plus the two threshold edges and the ceiling; and a check that each cap is half the gap between its two bases, as the statute implies. A transcription error fails the build.
- Not modeled. Married filing separately while living with a spouse (both thresholds are zero), lump-sum benefits for earlier years, and the deduction side of the return. Educational, not advice.
Sources.
- 1. Social Security Administration (Federal Register, 90 FR 49047), Cost-of-Living Increase and Other Determinations for 2026, November 3, 2025. The 2.8% COLA, the $184,500 contribution and benefit base, the retirement earnings test exempt amounts, and the quarter-of-coverage amount. Retrieved September 4, 2026; verified September 4, 2026.
- 2. United States Code (Cornell LII), 26 U.S.C. § 86(c) — Base amount and adjusted base amount for taxing Social Security benefits. The $25,000 / $32,000 and $34,000 / $44,000 thresholds, which are not indexed. Retrieved September 4, 2026; verified September 4, 2026.
Revision history.
This tool reads the annual numbers record; its history is below.
- September 5, 2026
- Added the senior deduction's phase-out rate (6 percent of MAGI over the threshold), which the widow's penalty and QCD tools apply.
- September 4, 2026
- First release of the annual numbers record and page for 2026, and of the IRMAA tool built on its Medicare section: plan and IRA limits from Notice 2025-67, HSA figures from Rev. Proc. 2025-19, Social Security figures from the Federal Register notice, Medicare premiums and both income-related tables from the CMS fact sheet, the standard deduction and gift exclusion from Rev. Proc. 2025-32, and the senior deduction from the IRS's OBBBA guidance.
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