For years, retirement advisors built Roth conversion strategies around a single ticking clock: the 2017 Tax Cuts and Jobs Act (TCJA) was scheduled to sunset after 2025, and brackets were widely expected to revert to higher pre-2018 levels in 2026. "Convert now while rates are low" became the rallying cry for anyone with a sizable traditional IRA or 401(k).
That clock stopped on July 4, 2025, when the One Big Beautiful Bill Act (OBBBA) was signed into law and permanently extended the TCJA bracket structure. The seven brackets — 10%, 12%, 22%, 24%, 32%, 35%, and 37% — no longer have a sunset date, according to analysis from Boldin and Mercer Advisors. The higher standard deduction and the expanded estate and gift tax exemption were also locked in.
So is the Roth conversion case dead? Not at all. The urgency argument is gone, but the structural argument — which was always the stronger one — remains fully intact.
The 2026 Bracket Landscape
Knowing where the bracket lines fall is the foundation of any conversion strategy. For 2026, single filers cross into the 22% bracket at $50,401 of taxable income and the 24% bracket at $105,701. Married couples filing jointly hit 22% at $100,801 and 24% at $211,401, according to IRA Financial.
That MFJ jump from 24% to 32% at the top of the bracket is the cliff most retirees want to avoid. A couple with $97,200 in taxable income could convert up to roughly $114,200 from a traditional IRA without leaving the 24% bracket — a meaningful chunk of tax-deferred money moved to a tax-free account at a known, locked-in rate.
Why the Structural Case Still Wins
Even with rates frozen, three forces push future taxable income higher for most retirees:
- Required Minimum Distributions. RMDs currently begin at age 73 and rise to 75 in 2033 for those born in 1960 or later, per T. Rowe Price. Once they start, the IRS dictates a growing share of your traditional balance each year — often pushing retirees into higher brackets they had previously avoided.
- Social Security taxation. Up to 85% of benefits become taxable once provisional income crosses modest thresholds. Large traditional balances combined with RMDs frequently trigger this.
- Surviving spouse compression. When one spouse dies, the survivor typically files as single — with bracket thresholds roughly half as wide. A perfectly comfortable joint tax picture can become punitive overnight.
Roth conversions done strategically in the gap between retirement and RMD age address all three. The money grows tax-free, never requires distributions during the original owner's lifetime, and doesn't add to provisional income for Social Security taxation.
Bracket Filling: The Core 2026 Strategy
The dominant technique is bracket filling — converting exactly enough each year to top off your current bracket without spilling into the next one. SDO CPA describes it as the disciplined alternative to large lump-sum conversions, which often create wasted tax at higher marginal rates.
Practical guidelines for 2026:
- Map your gap years. The window between retirement (often 60s) and RMDs (73 or 75) is prime conversion territory. Income is typically lowest, and you have maximum control over taxable events.
- Watch IRMAA cliffs. Medicare's income-related premium surcharges kick in at hard thresholds two years after the income year. A conversion that nudges 2026 income $1 over a threshold can cost thousands in 2028 Medicare premiums.
- Pay conversion taxes from outside the IRA. Using taxable-account cash to cover the tax bill leaves more dollars compounding tax-free inside the Roth.
- Stage conversions across multiple years. A single big conversion almost always wastes higher brackets. Spreading the same total over five or ten years usually saves five-figure tax amounts.
The Bottom Line
TCJA permanence didn't eliminate the Roth conversion opportunity — it eliminated the panic. The investors who benefit most in 2026 are the ones who run the numbers calmly, fill brackets deliberately during their low-income years, and avoid the IRMAA and Social Security traps that turn a smart conversion into an expensive one. The clock isn't ticking on tax rates anymore. But it is ticking on your gap years, and that's the window that matters.
Sources: Mercer Advisors, Boldin, IRA Financial, SDO CPA, T. Rowe Price