Projected 2027 federal tax brackets

What's still pending: the twelve months the 2027 figures are built from

The law adjusts tax figures using an average of twelve monthly readings of a price index called the Chained CPI for All Urban Consumers, or C-CPI-U. For tax year 2027 the twelve months run from September 2025 through August 2026. Here is every one of them, with the value, when it was published, and where it came from.

"Vintage" matters more than it looks. The government issues this index first as initial, then revises it to interim, and only finalises it about a year later. The IRS computes from the values as published at the time, so a figure derived from initial readings can move even after every month is out.

The month that was never measured

October 2025 does not exist. There is no October 2025 value in the published C-CPI-U series: the month is simply absent between September 2025 and November 2025. The documented cause is the 2025 lapse in appropriations, which stopped price collection for October; the scheduled October release (13 November 2025) was cancelled rather than rescheduled, unlike the November 2025 release, which was moved from 10 December to 18 December and did appear.

This matters more than a footnote. The law describes the value for a year as the average of the index “as of the close of the 12-month period ending on August 31”, and one of those twelve months was never measured. Whatever the IRS does about it, and it has not said, an eleven-month average is not the twelve-month average the statute describes.

The tax publishers listed further down say what they did: each averaged the 11 months that exist. That is their choice, not an IRS ruling. A 2027 figure that does not say how it handled this month has still made a choice; it just has not told you which.

We will update this page when the IRS or BLS says something on the record about it, and not before.

How this is computed

Three rules do all the work, and all three are in the tax code rather than in anyone's spreadsheet.

1. The twelve months are fixed by statute

“The C-CPI-U for any calendar year is the average of the C-CPI-U as of the close of the 12-month period ending on August 31 of such calendar year.”26 U.S.C. § 1(f)(6)(B) — read the statute

That sentence is what pins the window to September 2025 through August 2026 and no other twelve months. It is also why the professional publishers release their first 2027 estimates in September and not before: the last month of the window is not published until then.

2. The adjustment is measured from a fixed year, not from last year

“The cost-of-living adjustment for any calendar year is the percentage (if any) by which— (i) the C-CPI-U for the preceding calendar year, exceeds (ii) the CPI for calendar year 2016, multiplied by the amount determined under subparagraph (B).”26 U.S.C. § 1(f)(3)(A) — read the statute

This is the part most write-ups get wrong. The law does not take last year's bracket and grow it. It takes the original statutory dollar amount and grows it by the change since 2016, every year, from scratch.

3. The increase is rounded down, in steps of $50

“If any increase determined under paragraph (2)(A), section 63(c)(4), section 68(b)(2) or section 151(d)(4) is not a multiple of $50, such increase shall be rounded to the next lowest multiple of $50.”26 U.S.C. § 1(f)(7)(A) — read the statute

“In the case of a married individual filing a separate return, subparagraph (A) (other than with respect to sections 63(c)(4) and 151(d)(4)(A)) shall be applied by substituting "$25" for "$50" each place it appears.”26 U.S.C. § 1(f)(7)(B) — read the statute

Note what is rounded: the increase, not the final amount, and it is rounded down to the next lowest multiple of $50 rather than to the nearest one. The standard deduction follows the same $50 step under its own provision:

“If any increase under this clause is not a multiple of $50, such increase shall be rounded to the next lowest multiple of $50.”26 U.S.C. § 63(c)(7) (rounding clause), as amended by P.L. 119-21 (One Big Beautiful Bill Act) — read the statute

The known limitation, in plain English

Because the law works cumulatively from a fixed base year, a shortcut that takes the 2026 brackets and multiplies them by one year of inflation is not the same calculation. The 2026 figures have already been rounded down once. Growing an already-rounded number and rounding again can land one $50 step away from what the IRS publishes, on some thresholds but not others. Any projection built that way — including one we might publish here later — is right to the dollar on most lines and can be $50 out on a few. We would rather tell you that up front than present a table that looks more precise than it is.

We can show you the arithmetic but not an answer of our own: the first step is the average of the 12 monthly values over September 2025 through August 2026, and October 2025 does not exist, so the twelve-month average the law describes cannot be taken. Everything downstream of it, the factor, the thresholds and the standard deduction, is blocked on the same step. The build for this site refuses to render a projected dollar amount of its own while any month is missing; that refusal is a test, not a policy.

Projected 2027 figures from tax publishers

Projected 2027 income tax brackets

For single filers and married couples filing jointly, all three publishers project exactly the same brackets. For heads of household, Wolters Kluwer and Thomson Reuters project the same brackets; Bloomberg Tax’s are not in the public material we could check. Matching figures are not independent confirmation: the publishers all worked from the same published price data.

Each band is taxable income, meaning your income after deductions. Only the part of your income inside a band is taxed at that band’s rate.

Projected 2027 standard deduction

The publishers disagree on one line, head of household: Thomson Reuters projects $24,900 and Wolters Kluwer projects $24,950, while Bloomberg Tax prints $24,925 with $24,950 in parentheses and does not say what the second figure means. We do not pick between them. The official IRS figures will replace all three projections, and may not match any of them.

Where these figures come from

Last checked for new or revised projections on October 2, 2026.

There is also a category of site worth naming without linking to. Several pages ranking for "2027 tax brackets" today publish a full set of dollar figures derived from a flat inflation rate with no stated window, no month list, and no source. A rate quoted to two decimal places with nothing behind it is not a projection, it is a guess with a table around it. The test to apply to any 2027 figure you find, including every one on this page: can you see which months it used, and can you click through to them?

When the real numbers arrive

The IRS publishes the official tax-year-2027 amounts in a Revenue Procedure. There is no announced date. The last four have landed anywhere from early October to early November, and the 2026 figures came out in Rev. Proc. 2025-32 on October 9, 2025. When the 2027 procedure lands, the content on this page, including the publishers' projections above, is replaced with the official figures. A projection does not quietly turn into a fact, and nothing here flips automatically.

In the meantime, the numbers that are official and final today are the 2026 ones, and they are the ones that govern the return you file next spring: see the official 2026 federal tax brackets.

What you can actually do with this today

• Working out what you take home now: paycheck calculator for your state.
• A bonus coming: bonus tax calculator.
• Reading a W-2 and wondering why the wage boxes disagree: Box 1 vs Box 3 vs Box 5.
• Social Security's 2027 increase runs on a different index and a different window: 2027 COLA estimate and calculator.