2027 Roth IRA and IRA deduction phase-outs: the formula, closed
The 2027 Roth IRA and IRA deduction phase-out ranges run on the tax-bracket clock, not the 401(k) one, and the August CPI just closed it.
Every year, the same two questions arrive in September without anyone actually deciding the answer: what will the Roth IRA income limit be next year, and what will the traditional IRA deduction phase out at. Both get treated as mysteries the IRS reveals in the fall. They are not. The short answer: both phase-out families are indexed to the identical twelve-month inflation window that already set the 2027 tax brackets — not the third-quarter window that decides next year’s 401(k) limit — and with the Bureau of Labor Statistics’ August chained CPI now published, three of the four dollar ranges are arithmetic rather than forecast.
The clock nobody checks
Coverage of these numbers almost always assumes they move on the same schedule as the 401(k) and IRA contribution caps, because all of it lands in the same autumn news cycle. It does not. The Roth IRA phase-out is indexed under 26 U.S.C. § 408A(c)(3)(D), and the traditional IRA deduction phase-out under § 219(g)(8). Both provisions use the same borrowed language, adjusting their dollar amounts “by the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, determined by substituting ‘calendar year 2005’ for ‘calendar year 2016.’”
Section 1(f)(3) is the tax-bracket formula. It is the twelve-month average of the Chained Consumer Price Index for All Urban Consumers ending in August, the same window our 2027 IRS inflation adjustments tracker uses for the brackets, the standard deduction, the FSA cap, and the gift exclusion. The August 2026 reading — the twelfth and final month of that window — has already been published, which means the phase-out ranges close on the same day the brackets do, not on the September reading that decides the 401(k) limits, covered in the 2027 401(k) and IRA contribution limit projection. Those 401(k) limits run on a separate provision, § 415(d), measuring a third-quarter average that will not finish until September 30. The IRA limit is the exception: it rides the August window with the brackets. Two different IRS numbers, both due in a November notice, arrive from two different BLS releases a month apart. Conflating them is the single most common error in coverage of these figures.
The base years differ from the tax-bracket window, though the mechanics are shared. Section 1(f)(3)(B) directs that a base year before 2017 be reconstructed by taking the regular CPI-U for the applicable window and multiplying it by the ratio between the 2016 chained index and the 2016 regular index — 0.569845. For “calendar year 2005,” that means the CPI-U average for September 2004 through August 2005, 192.7667, multiplied by 0.569845, giving a base of 109.8472. Both the Roth and IRA provisions use that identical 2005 base; nothing about the phase-out math differs between them beyond the dollar amounts they start from.
What the statute actually sets
The dollar figures being adjusted are written directly into the two sections:
| Program | Filing status | Base amount | Range width |
|---|---|---|---|
| Roth IRA (§408A(c)(3)(B)) | Single / head of household | $95,000 | $15,000 |
| Roth IRA | Married filing jointly | $150,000 | $10,000 |
| Roth IRA | Married filing separately | $0 | $10,000 (not indexed) |
| IRA deduction, active participant (§219(g)(3)(B)) | Single / head of household | $50,000 | $10,000 |
| IRA deduction, active participant | Married filing jointly | $80,000 | $20,000 |
| IRA deduction, spouse not an active participant (§219(g)(7)) | — | $150,000 | $10,000 |
| IRA deduction | Married filing separately | $0 | $10,000 (not indexed) |
Both statutes round the adjusted dollar amount to the nearest multiple of $1,000. The width of each range — $15,000, $10,000, or $20,000 — is fixed in the statute and is not itself adjusted for inflation; only the floor of the range moves.
Checking the method: four for four against the confirmed 2026 figures
Before trusting a formula to project 2027, it needs to reproduce 2026, which the IRS already set in Notice 2025-67. The 2026 window average — the same interim BLS figure the tax-bracket tracker used to reproduce the 2026 brackets exactly — is 177.11. Divided by the 109.8472 base, that is a ratio of 1.612332.
| Amount | Ratio × base | Rounded to nearest $1,000 | Official 2026 floor |
|---|---|---|---|
| $95,000 (Roth single) | 95,000 × 1.612332 = 153,171 | $153,000 | $153,000 ✓ |
| $150,000 (Roth joint / IRA spouse) | 150,000 × 1.612332 = 241,850 | $242,000 | $242,000 ✓ |
| $50,000 (IRA single) | 50,000 × 1.612332 = 80,617 | $81,000 | $81,000 ✓ |
| $80,000 (IRA joint) | 80,000 × 1.612332 = 128,987 | $129,000 | $129,000 ✓ |
Four inputs, four outputs, four exact matches against the confirmed 2026 ranges ($153,000–$168,000 Roth single; $242,000–$252,000 Roth joint; $81,000–$91,000 IRA single; $129,000–$149,000 IRA joint). The same statute, applied to the same window, produces the numbers the IRS already published. That is what makes the 2027 run below more than a guess.
The 2027 numbers, both ways
The twelve months from September 2025 through August 2026 are now complete, except for one: the Bureau of Labor Statistics never published an October 2025 index, because data collection stopped during that year’s government shutdown. Averaging the eleven months that exist gives 182.8565; filling the gap with an estimate for the missing month, as our inflation tracker explains in full, gives 182.6293 instead. That difference of roughly a tenth of a percent is the only thing left undecided in this projection, and it moves the ratio from 1.66465 (eleven months) to 1.66258 (October imputed).
| Amount | Eleven-month factor (1.66465) | With October imputed (1.66258) | 2027 range |
|---|---|---|---|
| $95,000 (Roth single/HoH) | 95,000 × 1.66465 = 158,142 → $158,000 | 95,000 × 1.66258 = 157,945 → $158,000 | $158,000–$173,000, either way |
| $150,000 (Roth joint) | 150,000 × 1.66465 = 249,698 → $250,000 | 150,000 × 1.66258 = 249,387 → $249,000 | $250,000–$260,000 or $249,000–$259,000 |
| $50,000 (IRA single/HoH) | 50,000 × 1.66465 = 83,233 → $83,000 | 50,000 × 1.66258 = 83,129 → $83,000 | $83,000–$93,000, either way |
| $80,000 (IRA joint) | 80,000 × 1.66465 = 133,172 → $133,000 | 80,000 × 1.66258 = 133,006 → $133,000 | $133,000–$153,000, either way |
| $150,000 (IRA spouse not covered) | same as Roth joint | same as Roth joint | $250,000–$260,000 or $249,000–$259,000 |
Three of the five rows land on the same rounded figure regardless of which reading the IRS uses, because they sit far enough from a $1,000 rounding line that a tenth-of-a-percent shift in the average does not cross it. The joint Roth range, and the spouse-not-covered IRA range, are the exception: $249,697.50 with the eleven-month average sits just above the $249,500 rounding line, while $249,386.55 with October imputed sits just below it — a gap of roughly $311 deciding whether the top of the range reads $259,000 or $260,000. The IRA joint figure came closest to flipping without actually doing so: $133,006 under the imputed reading is only $6 above the $133,000 floor, the tightest margin in the table, but not tight enough to change the outcome.
A different clock than the 401(k) limit — and the Saver’s Match
It is easy to read these ranges as separate from the IRA contribution limit, but the two share a calendar. The limit is indexed under 26 U.S.C. 219(b)(5)(C), which borrows the section 1(f)(3) cost-of-living adjustment with 2007 as the base year, so it runs on the same twelve months ending in August as the ranges and rounds down to a multiple of $500. On the eleven months that exist, that projects to $7,500 for 2027, unchanged from 2026 (it would take an index average near 186.8 to reach $8,000). It is not the third-quarter CPI-U average that sets the 401(k) limit; our 2027 401(k) and IRA contribution limit projection lays out the two clocks. A filer whose MAGI is inside the phase-out range above is working against the $7,500 ceiling projected there, reduced by the fraction below — the phase-out sets how much of that ceiling is available, not the ceiling itself.
2027 is also the year the Saver’s Credit is replaced by the Saver’s Match, a separate, lower-income incentive with its own eligibility thresholds that are not the same as the Roth or IRA deduction phase-outs discussed here. The two systems apply to different income bands and should not be confused.
What the range means for a specific filer
The reduction inside the range is linear, and the statute spells out the arithmetic directly: the contribution limit is reduced by the same proportion that the excess of MAGI over the floor bears to the width of the range.
Take a single filer with a 2027 MAGI of $165,000, against the projected range of $158,000 to $173,000. The statute’s reduction ratio is the excess of MAGI over the floor, as a fraction of the range width: $165,000 − $158,000 = $7,000, and $7,000 / $15,000 = 46.7%. That is the fraction of the $7,500 limit the phase-out removes, leaving 53.3% intact: (1 − 0.467) × $7,500 = 8,000/15,000 × $7,500 = $4,000.00. The IRS worksheet in Publication 590-A applies its own further rounding to reach the exact dollar figure a filer would enter on their return, a mechanic this projection has not independently verified in the statute text and does not state as fact here. This example lands on a round figure, so rounding should matter little, and the underlying fraction, roughly 53% of the limit remaining, is fixed by the statute regardless of that final rounding step.
This is also the point where the backdoor Roth strategy becomes relevant for anyone above the top of the range entirely. A filer with MAGI over $173,000 (single) or $260,000 (joint) cannot contribute to a Roth IRA directly at all, which is why the backdoor Roth IRA — a nondeductible traditional IRA contribution converted to Roth — exists as a workaround, and why the pro-rata rule matters enormously to anyone who has other pre-tax IRA money sitting around. The conversion step itself does not count against next year’s phase-out either: as confirmed above, § 408A(c)(3)(B)(i) explicitly excludes amounts included in gross income under the rollover-and-conversion provision from the MAGI used for this test. For the general definition of modified AGI and how it differs across programs, see the MAGI guide; for the underlying difference between the two account types these ranges apply to, see Roth vs. traditional IRA and the broader Roth IRA explainer. Anyone who contributes directly to a Roth IRA and later discovers their MAGI landed above the ceiling has a fix, and it is time-sensitive: see how to correct an excess Roth contribution.
The calendar from here
The eleven-versus-imputed question was answered on November 5, 2026, when Rev. Proc. 2026-35 published the 2027 brackets and the other figures that run on this formula using the average of the eleven published months; our inflation adjustments tracker compares each of them with the projection. The phase-out ranges themselves are not in that revenue procedure. They come in the separate retirement-plan notice, which a year earlier arrived in November (Notice 2025-67) and which had not been published as of November 11, 2026. Until it is, this page remains a projection, now pointing to the eleven-month column. Watch the tracker for the notice, and the 401(k) and IRA contribution limit projection for the separate September data point that settles the 401(k) limits, and for the IRA ceiling projected there.
Correction, November 11, 2026: An earlier version said the 2027 IRA contribution limit ran on a different calendar from these phase-out ranges and used an $8,000 limit in its example. Both are indexed on the same August window, the limit projects to $7,500, and the example has been recalculated.
Sources
- 26 U.S.C. § 408A(c)(3) — law.cornell.edu/uscode/text/26/408A
- 26 U.S.C. § 219(g) — law.cornell.edu/uscode/text/26/219
- 26 U.S.C. § 1(f)(3) — law.cornell.edu/uscode/text/26/1
- Bureau of Labor Statistics, Chained CPI-U and CPI-U series (SUUR0000SA0, CUUR0000SA0) — api.bls.gov/publicAPI/v2/timeseries/data/
- IRS Notice 2025-67 (2026 retirement plan cost-of-living adjustments) — cited for the confirmed 2026 control figures; document text not independently re-verified for this piece beyond the figures already reproduced in this site’s 401(k) and IRA contribution limit projection
- finbarrow, IRS 2027 inflation adjustments tracker — companion page for the shared CPI window and the October 2025 imputation question
Quick answers
What are the 2027 Roth IRA income phase-out ranges?
On the CPI data published through August 2026, single and head-of-household filers phase out between $158,000 and $173,000 of modified AGI, and joint filers between $250,000 and $260,000 (or $249,000 to $259,000 if the unpublished October 2025 month were filled with an estimate instead of averaging the eleven months that exist; on November 5, 2026, Rev. Proc. 2026-35 showed the IRS averaging the eleven months for the 2027 figures it indexed with this formula). Three of those four numbers do not move regardless of which approach the IRS takes; only the joint figures depend on it. The IRS confirms the official 2027 ranges in a notice expected in November 2026.
What are the 2027 traditional IRA deduction phase-out ranges?
For an active plan participant filing single or head of household, the deduction phases out between $83,000 and $93,000 of modified AGI. For an active participant filing jointly, between $133,000 and $153,000. For a spouse who is not covered by a workplace plan but whose spouse is, the range is $250,000 to $260,000 (or $249,000 to $259,000 under the alternative October treatment), the same figures as the Roth joint range because both use the identical $150,000 statutory base.
Why do the Roth and IRA phase-outs use a different CPI window than the 401(k) limits?
The phase-out ranges are indexed under 26 U.S.C. 408A(c)(3)(D) and 219(g)(8), both of which borrow the cost-of-living formula in section 1(f)(3) — the same twelve-month window ending in August that sets the tax brackets and standard deduction. The 401(k)-type limits, by contrast, are indexed under section 415(d) using a third-quarter average of a different CPI series. The IRA contribution limit is not one of them: section 219(b)(5)(C) runs it on the same August window, so the IRA limit and the phase-outs move together.
Is the 2027 Roth IRA joint phase-out range locked in yet?
Almost. The single, head-of-household, and active-participant IRA deduction ranges land on the same $1,000 rounding step whether or not October 2025, a month the Bureau of Labor Statistics never published because of the government shutdown, is filled with an estimate. The joint Roth range and the non-covered-spouse IRA range depended on that choice: $250,000 to $260,000 with the eleven published months, $249,000 to $259,000 with October imputed. Rev. Proc. 2026-35, released November 5, 2026, averaged the eleven months for the 2027 brackets and the other figures built on the same formula, which points to $250,000 to $260,000. The retirement-plan notice that formally states these ranges was still pending on November 11, 2026.
Does converting a traditional IRA to a Roth IRA count toward the MAGI that triggers the phase-out?
No. Section 408A(c)(3)(B)(i) defines the modified adjusted gross income used for this phase-out by cross-reference to section 219(g)(3), "except that any amount included in gross income under subsection (d)(3) shall not be taken into account" — and subsection (d)(3) is the rollover-and-conversion provision. A large Roth conversion therefore does not itself push a filer into or through the phase-out range for a direct Roth contribution in the same year, which is the statutory mechanism the backdoor Roth strategy relies on.
What happens to my Roth IRA contribution limit if my MAGI falls inside the 2027 phase-out range?
The limit shrinks in direct proportion to how far into the range your MAGI sits. For a single filer with the 2027 range projected at $158,000 to $173,000, a MAGI of $165,000 sits $7,000 above the $158,000 floor, out of a $15,000-wide range, or 46.7% of the way through. That leaves 53.3% of the full $7,500 projected contribution limit available, or $4,000, before any additional rounding the IRS worksheet in Publication 590-A applies to the final dollar figure.
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