2027 tax brackets: projected IRS inflation adjustment of +3.23%
The IRS indexes federal income-tax brackets and the standard deduction with the chained CPI-U (IRC §1(f)): the average C-CPI-U for the twelve months ending August 2026 divided by the prior twelve-month average, each as published in that September's CPI release. With 10 of the twelve months printed and 1 carried by the Nowflation nowcast (Oct 2025 was never published by BLS because of the federal shutdown), the factor is 1.032327 — an adjustment of 3.2327% against 2.275% for 2026. Applied to the 2026 amounts in IRS Rev. Proc. 2025-32 (announced Oct 9, 2025) with the statutory rounding (brackets down to $25, standard deduction to $50), the projected 2027 thresholds are below. The factor locks with the August CPI release (Sep 11, 2026); the IRS publishes the official amounts in October.
Single
| Rate | 2026 (Rev. Proc. 2025-32) | 2027 projected | Change |
|---|
| 10% | up to $12,400 | up to $12,800 | +$400 |
| 12% | up to $50,400 | up to $52,025 | +$1,625 |
| 22% | up to $105,700 | up to $109,100 | +$3,400 |
| 24% | up to $201,775 | up to $208,275 | +$6,500 |
| 32% | up to $256,225 | up to $264,500 | +$8,275 |
| 35% | up to $640,600 | up to $661,300 | +$20,700 |
| 37% | above the 35% bracket | above the 35% bracket | — |
| Standard deduction | $16,100 | $16,600 | +$500 |
Married filing jointly
| Rate | 2026 (Rev. Proc. 2025-32) | 2027 projected | Change |
|---|
| 10% | up to $24,800 | up to $25,600 | +$800 |
| 12% | up to $100,800 | up to $104,050 | +$3,250 |
| 22% | up to $211,400 | up to $218,225 | +$6,825 |
| 24% | up to $403,550 | up to $416,575 | +$13,025 |
| 32% | up to $512,450 | up to $529,000 | +$16,550 |
| 35% | up to $768,700 | up to $793,550 | +$24,850 |
| 37% | above the 35% bracket | above the 35% bracket | — |
| Standard deduction | $32,200 | $33,200 | +$1,000 |
Head of household
| Rate | 2026 (Rev. Proc. 2025-32) | 2027 projected | Change |
|---|
| 10% | up to $17,700 | up to $18,250 | +$550 |
| 12% | up to $67,450 | up to $69,625 | +$2,175 |
| 22% | up to $105,700 | up to $109,100 | +$3,400 |
| 24% | up to $201,750 | up to $208,250 | +$6,500 |
| 32% | up to $256,200 | up to $264,475 | +$8,275 |
| 35% | up to $640,600 | up to $661,300 | +$20,700 |
| 37% | above the 35% bracket | above the 35% bracket | — |
| Standard deduction | $24,150 | $24,900 | +$750 |
The factor since the switch to chained CPI
| Tax year | Window | Adjustment (as published) | On today's revised data |
|---|
| 2018 | Sep 2016–Aug 2017 | 1.747% | 1.65% |
| 2019 | Sep 2017–Aug 2018 | 1.941% | 1.993% |
| 2020 | Sep 2018–Aug 2019 | 1.589% | 1.551% |
| 2021 | Sep 2019–Aug 2020 | 1.001% | 1.142% |
| 2022 | Sep 2020–Aug 2021 | 3.115% | 2.934% |
| 2023 | Sep 2021–Aug 2022 | 7.081% | 7.256% |
| 2024 | Sep 2022–Aug 2023 | 5.402% | 5.278% |
| 2025 | Sep 2023–Aug 2024 | 2.789% | 2.792% |
| 2026 | Sep 2024–Aug 2025 | 2.275% | 2.422% |
| 2027 (projected) | Sep 2025–Aug 2026 | 3.233% | 3.179% |
The IRS uses chained CPI-U values as published in that September's CPI release, and C-CPI-U months are revised for up to a year after they first print. The Sep 2024–Aug 2025 average is therefore taken from the 2025-09-11 release (177.1137); today's revised values average 177.2058. This vintage-true method reproduces the year-over-year change in every published bracket top since 2019 to within rounding — last year's factor recomputes as 2.275%. Chained CPI-U months are published as "initial" values and revised quarterly for up to a year; the current window uses the latest published vintage plus the nowcast month. BLS never published an October 2025 index (federal shutdown): the 12-month average uses the published months, and the payload also carries the factor with that month linearly interpolated. Sources: BLS chained CPI-U via FRED/ALFRED (SUUR0000SA0), IRS Rev. Proc. 2025-32, IRC §1(f), the Nowflation nowcast. Projections, not promises. The COLA is set by the Social Security Administration with the September CPI; I-Bond rates by the Treasury on the first business day of November and May; tax-year amounts by the IRS in a revenue procedure each fall. The IRS indexes from statutory base-year amounts with cumulative factors and rounds once, so chaining from the published 2026 amounts can differ from the official 2027 figures by one rounding step ($25 / $50). Chained CPI-U initial values are revised. Not tax, benefits or investment advice. Every call is graded on the scoreboard after the announcement.
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