Staged Roth Conversions in 2026: Updated Step‑by‑Step Strategy

What you'll learn: how to plan and execute staged Roth conversions in 2026 using a multi‑year, tax‑bracket approach that accounts for recent policy context (SECURE 2.0 RMD timing, unchanged recharacterization rules), MAGI interactions (NIIT, IRMAA, ACA), and practical execution tactics. This guide is written for tax‑planning enthusiasts and advisers who want an actionable, current playbook for September 2026.

Prerequisites and context

Before you begin: gather recent tax returns, year‑to‑date income statements, retirement account balances, and state tax rules. Two items of particular relevance in 2026:

• RMD timing under SECURE 2.0: Required minimum distribution ages were increased by SECURE 2.0; as of 2026, the effective RMD start age for many taxpayers is 73 (confirm your personal rules and plan type). Moving pre‑tax assets into Roth still reduces future RMD exposure and taxable RMD amounts.
• Recharacterizations: Roth conversions generally cannot be recharacterized (i.e., undone) under the law enacted after 2018. Treat conversions as irreversible for planning purposes unless future law or IRS guidance changes.

Other constants remain: the Net Investment Income Tax (NIIT) thresholds ($200,000 single, $250,000 married filing jointly) are still key trigger levels because they are not indexed, and IRMAA (Medicare surcharge) determinations continue to be based on tax‑return income from prior years (typically two years prior to the benefit year).

High‑level process (six steps)

1. Define objectives and horizon.
2. Project taxable income for 2026 and the next 2–4 years.
3. Find bracket space and set yearly conversion targets.
4. Simulate interactions (deductions, credits, NIIT, IRMAA, capital gains, state tax).
5. Plan withholding and estimated taxes.
6. Execute, document and monitor—adjust mid‑year if needed.

Step‑by‑step

1. Set objectives and horizon

Be explicit: are you converting to maximize lifetime tax savings, reduce taxable RMDs, create a tax‑diversified withdrawal strategy, or eliminate future required distributions? The time horizon matters. If you expect to live decades in retirement, the long‑term tax‑free growth in a Roth often outweighs short‑term tax costs; if you expect large near‑term medical expenses or need to preserve income‑tested benefits (ACA subsidies), you may proceed more slowly.

2. Project taxable income for 2026 and nearby years

Build a conservative, line‑by‑line projection for each year you plan to do conversions. Include:

• Wages, bonuses, self‑employment income and expected business income.
• Ordinary dividends, taxable interest.
• Planned capital gains realizations (note long‑term gains use taxable income thresholds).
• Social Security, pensions and planned retirement distributions.
• Rental income, pass‑through K‑1 income and itemized deductions vs. the standard deduction.

Run the projection for both filing‑status scenarios if your status may change (marriage, divorce, spouse death). For thresholds and bracket endpoints, use the IRS 2026 inflation‑adjusted tables and your state revenue department for state brackets.

3. Identify bracket space and set yearly conversion targets

Goal: move just enough pre‑tax money into Roth each year to fill a favorable marginal bracket (or other target band tied to capital‑gains thresholds) without creating a larger, avoidable tax bill.

1. Choose the marginal bracket or taxable‑income band you want to fill (for example: the 12% federal bracket, or the threshold that keeps you under the 0% long‑term capital‑gains band in a sale year).
2. Subtract projected pre‑conversion taxable income from the chosen bracket top to find “space.”
3. Plan a conversion amount that fills most of that space, keeping a buffer for unplanned income (bonuses, K‑1s, unforeseen capital gains).

Example (illustrative): Married filing jointly, projected taxable income before conversion = $145,000. If your target is to remain in the 12% bracket and the bracket top (per IRS 2026 tables) is X, available space = X − 145,000. Convert up to that space less a reserve—e.g., convert $30,000 now and review mid‑year.

Why the "space" approach works

Filling bracket space reduces the marginal tax rate on the converted dollars and preserves eligibility for income‑sensitive benefits or capital‑gains bands. Because long‑term capital‑gains rates are determined by taxable income, keeping ordinary income under certain thresholds can preserve 0% or 15% rates on planned gain realizations.

4. Simulate interactions: deductions, credits, NIIT, IRMAA, capital gains and state tax

Run multi‑year simulations (tax software, spreadsheet or CPA model) that show:

• How conversions affect itemized deductions with AGI floors (medical expenses, casualty losses).
• Phaseouts for credits (education credits, child tax credits) and their value under different AGI paths.
• NIIT exposure: Because the NIIT applies based on MAGI and statutory thresholds, conversions can trigger the 3.8% surtax even when ordinary rates stay modest.
• IRMAA: Medicare Part B/D surcharges are determined from tax returns filed two years earlier. A conversion in 2026 may affect Medicare premiums beginning in 2028 if it raises MAGI above IRMAA thresholds.
• State income tax: some states tax Roth conversions fully as ordinary income and do not decouple; others have special rules—check your state’s 2026 guidance.

Run at least three scenarios: conservative (smaller conversions), base case (planned bracket fill), and aggressive (larger conversion). Compare after‑tax wealth and benefit impacts across scenarios.

5. Plan withholding and estimated taxes

Because Roth conversions add ordinary income, they can create underpayment penalties when not matched by withholding or estimated payments. Key rules to remember:

• Safe‑harbor: pay 90% of current‑year tax or 100% of prior‑year tax to avoid underpayment penalties; taxpayers with higher AGI must pay 110% of prior‑year tax. Confirm the 110% threshold for 2026 (it has historically applied at $150,000 AGI).
• Withholding vs. estimated payments: custodial withholding reduces the amount converted. If you want the full dollars inside Roth, do a trustee‑to‑trustee conversion and make estimated payments instead.
• Timing: make estimated payments on the quarterly schedule or increase payroll withholding to cover conversion tax. If a large conversion occurs late in the year, split the estimated payment to avoid quarter‑end penalties.

Example: You plan a $50,000 conversion taxed mainly at 22%—projected tax ≈ $11,000. If you want the entire $50k converted, avoid withholding on the distribution and make estimated tax payments totaling $11,000 across the relevant quarters.

6. Execute, document and monitor

Best practices for execution:

• Use trustee‑to‑trustee conversions where possible to avoid distribution withholding and simplify reporting.
• Retain all forms: 1099‑R, Form 5498 (custodian statements) and your conversion worksheets. File Form 8606 when you have non‑deductible IRA basis or conversions to report.
• If you have after‑tax basis in traditional IRAs, apply the pro‑rata rule: conversions are prorated across all pre‑tax and after‑tax IRA balances, which can create unexpected tax on "basis" dollars. Consider a pre‑conversion rollover of pre‑tax IRAs into an employer plan (401(k)) if your plan accepts rollovers—this can simplify the tax outcome.
• Monitor income mid‑year. If you realize unexpected K‑1/pass‑through income, reduce or delay remaining conversions for the year.

Common mistakes to avoid

• Converting without modeling NIIT and IRMAA effects — small increases in MAGI can carry outsized non‑income tax costs.
• Failing to consider the pro‑rata rule when you have mixed pre‑tax and after‑tax IRA balances.
• Withholding on the conversion distribution when you wanted the full amount converted; custodial withholding reduces the converted principal and can defeat the strategy.
• Counting on recharacterization — generally no longer available.
• Ignoring state tax differences; a federally attractive conversion can be costly in high‑tax states.

Pro tips

• Coordinate Roth conversions with planned capital‑gains sales: convert in years with low taxable ordinary income to preserve 0%/15% capital‑gains bands.
• If market volatility reduces account balances, a conversion during a market dip can convert fewer shares for the same taxable amount and capture subsequent tax‑free upside.
• For clients subject to IRMAA, consider spacing conversions across years and using life‑changing event exceptions (marriage, divorce, loss of income) to request IRMAA reconsideration if necessary.
• Use a rolling, multi‑year calendar: set automatic annual reminders to re‑run simulations after tax‑law, life or market changes.

Updated practical scenarios — September 2026

Scenario A — Near‑retirement couple smoothing bracket space

Married filing jointly, projected taxable income without conversions = $160,000. The couple wants to avoid a higher bracket and limit IRMAA risk later. They convert $30,000 in 2026, $30,000 in 2027, and $30,000 in 2028; each year they fill available bracket space after accounting for projected Social Security and planned itemized deductions. They fund the incremental tax with quarterly estimated payments and verify that the conversions do not push them over the NIIT thresholds.

Scenario B — Capital‑gain heavy single taxpayer

A single taxpayer expects a large long‑term gain from a business sale in 2027. Rather than converting a large sum in 2027 and pushing the gain into a higher capital‑gains bracket, they spread conversions in 2025–2026 to create room in 2027. The plan preserves a larger portion of the gain at the 15% capital‑gains rate.

Scenario C — Self‑employed contractor avoiding withholding loss

A self‑employed contractor prefers not to reduce the conversion by custodial withholding. They do trustee‑to‑trustee conversions and make estimated tax payments timed around the conversions; they also maintain a cash reserve to make up any shortfall if K‑1 income arrives late in the year.

Checklist before executing a staged conversion

• Run multi‑year tax projections including projected capital gains and itemized deductions.
• Confirm federal bracket thresholds and safe‑harbor rules for 2026 using IRS publications and your tax software.
• Model NIIT, IRMAA and ACA subsidy impacts across years; remember IRMAA looks at returns two years prior.
• Decide whether to withhold or use estimated payments; remember withholding reduces converted principal.
• Consider rolling pre‑tax IRAs into a 401(k) (if plan rules allow) to reduce pro‑rata complications.
• Coordinate with your spouse’s tax position and possible filing‑status changes.
• Document trustee‑to‑trustee transfers and save forms 1099‑R and 5498; file Form 8606 where required.
• Revisit the plan annually or after major life or market changes.

When to consult a planner or tax professional

Engage a CPA or tax planner when you face complex interactions: significant pass‑through income, business sales, multiple state tax jurisdictions, mixed basis IRAs (pro‑rata concerns), or if you are within sight of IRMAA or NIIT thresholds. A planner can run sensitivity analyses and advise on tactical moves such as pre‑conversion 401(k) rollovers or coordinated capital‑gains timing.

Bottom line

Staged Roth conversions remain a high‑value tool in 2026 for tax diversification, reducing future taxable RMDs and managing lifetime tax exposure. The key is precise projection, simulation of MAGI effects (NIIT, IRMAA, ACA), disciplined tax‑payment planning, and careful execution. With SECURE 2.0 in force and recharacterizations still generally disallowed, treat conversions as deliberate, irreversible moves and plan across multiple years to capture tax‑rate efficiencies.

FAQ

Can I recharacterize a Roth conversion in 2026?

No. Under the rules in effect after the 2017 tax act and through September 2026, Roth conversions generally cannot be recharacterized (undone). Plan conversions as effectively permanent and confirm current IRS guidance before acting.

How do Roth conversions affect Medicare IRMAA?

IRMAA surcharges are based on modified adjusted gross income (MAGI) reported on tax returns from two years earlier. A conversion in 2026 can influence Medicare premiums in 2028 if it raises MAGI above IRMAA thresholds. Model both the tax and premium consequences when planning conversions near IRMAA bands.

What is the pro‑rata rule and why does it matter?

The pro‑rata rule requires that conversions from traditional IRAs be treated as coming proportionally from pre‑tax and after‑tax IRA balances across all your IRAs. If you have after‑tax basis, you must file Form 8606 and may owe tax on the pre‑tax portion. Rolling pre‑tax IRAs into a 401(k) before conversion (if permitted) can reduce pro‑rata complexity.

Do state taxes change the conversion calculus?

Yes. State tax treatment varies—some states fully tax conversions as ordinary income; others may have nuances or decoupling provisions. Include state tax modeling in your simulations and, if applicable, consider timing or partial conversions to manage state tax exposure.

How should I handle withholding versus estimated taxes?

If you want the full dollar amount converted, avoid custodial withholding (which reduces conversion principal) and instead make estimated tax payments on the quarterly schedule. Use the safe‑harbor rules (90% of current year or 100%/110% of prior year) to avoid underpayment penalties. Adjust payroll withholding if you have wage income.