The single most consequential change to U.S. retirement tax planning in 2025 was not a new contribution limit or a benefit COLA. It was the One Big Beautiful Bill Act, signed July 4, 2025, which permanently extended the TCJA’s seven-bracket structure. The 10/12/22/24/32/35/37% rates are no longer scheduled to sunset.
For Roth conversion planning, that single legislative action erased one of the most cited urgency arguments of the 2020s — “convert before rates rise” — but it did not eliminate the underlying case for conversions. Per Kiplinger, Greenbush Financial Group, and the broader practitioner press, the 2026 question is no longer “is the strategy still alive?” It is “how should the playbook change?”
For advisors and clients sitting on traditional IRA balances, the answer matters. Here is the updated framework.
What the OBBBA Actually Did
The headline of the One Big Beautiful Bill Act is straightforward: it made the 2017 tax rate structure permanent. Three implications for retirement tax planning:
- No automatic 2026 reversion. The pre-2018 rates (which would have produced 15/25/28/33/35/39.6% brackets in 2026) no longer come back unless Congress takes new action.
- Higher standard deduction stays. The TCJA-era standard deduction levels remain in place, with annual inflation indexing. For 2026, that is $15,750 single / $31,500 married filing jointly.
- The new senior bonus deduction of $6,000 for taxpayers age 65+ (covered in our Social Security 2026 analysis) layers on top of these baselines.
The combination produces a tax environment in 2026 that is structurally lower-rate than the pre-TCJA baseline — and now, for the first time since 2017, that low-rate environment has no scheduled expiration.
Why “Convert Before Rates Rise” Is No Longer the Pitch
For nearly a decade, financial planners have framed Roth conversions around an impending sunset of the TCJA rates. The pitch was clean: convert at 24%, avoid the prospective 28% rate, capture a permanent tax-free withdrawal stream.
The OBBBA closed that argument. With no automatic reversion, the conversion case must now stand on its own merits — meaning the personal tax trajectory of the individual client, not the aggregate trajectory of the U.S. tax code.
Per Greenbush Financial Group’s 2026 guidance, the analysis now centers on three personal-trajectory questions:
- Will the client’s marginal tax rate at withdrawal (from RMDs and other income) be higher than today’s conversion rate?
- Does the client have sufficient non-IRA assets to pay the conversion tax without dipping into the IRA itself?
- Is the client’s estate plan structured to benefit from a tax-free Roth inheritance for heirs?
A “yes” to all three preserves the conversion case. A “no” on any one materially weakens it.
The Estate Planning Case Got Stronger, Not Weaker
Counter-intuitively, the OBBBA strengthens one specific Roth conversion argument: the estate planning case.
Three reasons:
- Roth IRAs have no required minimum distributions for the original owner. A converted balance can grow tax-free for the lifetime of the original retiree, then pass to heirs.
- Heirs receive Roth IRAs subject to the SECURE Act’s 10-year payout rule but no income tax. A traditional IRA inheritance is fully ordinary income to the heir; a Roth inheritance is tax-free.
- The 2026 federal estate tax exemption sits at approximately $13.99 million per individual ($27.98 million per couple), per the IRS’s 2026 inflation-adjusted figures. For estates approaching this threshold, the income-tax-saving for heirs of the Roth conversion can be substantially larger than the absolute estate tax savings.
For high-net-worth families, the conversion math now leans into the estate plan rather than the personal income tax projection. The Motley Fool’s recent estate planning piece highlights this re-framing as one of the dominant 2026 practitioner conversations.
The 50% Rate Trap
One technical point deserves explicit warning. Kiplinger has documented multiple client scenarios in 2025–2026 where the effective marginal rate on a Roth conversion climbed to 50% or higher because the conversion triggered overlapping tax phaseouts and surcharges.
The mechanics:
- The conversion increases AGI, potentially pushing more Social Security benefits into the taxable column
- Higher AGI can trigger or increase the Net Investment Income Tax (3.8% surcharge)
- Higher AGI can trigger IRMAA Medicare premium surcharges that add hundreds to thousands of dollars per year
- For high-income clients, the conversion can phase out or eliminate the Qualified Business Income deduction
A conversion that looks like a 24% federal-tax-bracket transaction can, in the wrong client circumstances, produce a 45–50% effective rate on the converted dollars. The point is not that conversions are dangerous. The point is that they need to be modeled, not assumed.
This is precisely the practitioner discipline the FPA Journal has been emphasizing for two years — and it is more important post-OBBBA than ever, because the easy “rates are going up anyway” rationalization no longer hides the underlying complexity.
How the Playbook Changes
For advisors running Roth conversion programs in 2026, three practical updates:
1. Multi-year ladders, not large one-time conversions
The OBBBA’s permanent rate environment removes the urgency to compress conversions into 2024–2025. Spreading conversions across 5–10 years, filling lower brackets without crossing into IRMAA or NIIT thresholds, becomes the dominant pattern. Per Greenbush, this is now the default recommendation for retirees who have not yet started RMDs.
2. Coordinate with Social Security claiming
For retirees in the 62–69 window, the order of operations matters. A client who converts before claiming Social Security can complete more conversion volume at lower marginal rates than one who converts while drawing benefits. The interaction with the 2026 Social Security framework is now central to the planning sequence.
3. Stress-test against the IRMAA and NIIT brackets
The 2026 Medicare IRMAA brackets and the 3.8% NIIT threshold should be hard limits in any conversion model. A conversion plan that ignores them produces the 50% effective-rate surprise. A conversion plan that respects them maintains the strategy’s after-tax return.
What This Means for Different Client Segments
Three client segments where the 2026 framework lands differently:
- Pre-retirees age 55–64: The conversion case is strongest here. Lower income years before Social Security claiming, multi-year runway to ladder, and decades of tax-free growth in the converted dollars. The OBBBA changes the urgency, not the underlying case.
- Recent retirees age 65–72: The senior bonus deduction makes the calculus more attractive than the pre-2026 framework would have implied. The interaction with RMDs starting at age 73 creates a tight planning window.
- High-net-worth retirees age 72+: The case shifts almost entirely to estate planning. Conversions are sized to optimize the tax cost of leaving Roth assets to heirs, not the personal income tax trajectory.
What Advisors Are Watching
Three practical questions to bring to the next client review:
- Has the firm’s standard Roth conversion modeling tool been updated to reflect the OBBBA’s permanent rate structure, or is it still implicitly assuming a 2026 sunset that no longer applies?
- For each client with a traditional IRA balance, has the conversion analysis included the IRMAA, NIIT, and Social Security taxation interactions — or only the headline marginal rate?
- For high-net-worth clients, has the estate planning case for Roth conversions been re-framed in light of the 2026 estate tax exemption levels and the SECURE Act’s 10-year payout rule for inherited IRAs?
The OBBBA did not kill Roth conversions. It made them a strategy that has to be earned through careful modeling rather than reflexive recommendation. That is, on net, a healthier framework for the practitioner profession — and a more demanding one. The advisors and firms updating their modeling discipline now will be the ones delivering the better outcomes for the next decade.
Sources: Kiplinger on Roth conversions in 2026; Kiplinger on the 50% rate trap; Greenbush Financial Group on 2026 timing; Federal News Network on 2026 Roth and TSP changes; The Motley Fool on 2026 estate planning; Fidelity 2026 retirement money moves.
