I’m 63 and a retired CPA. I have a $1.2 million 401(k). Do I need a Roth conversion?
Short answer: Maybe—but only if a thoughtful plan says your lifetime after-tax wealth is higher by paying some tax now. With a $1.2 million pre-tax balance and roughly 12 years before required minimum distributions (RMDs) begin at age 75 (for those born in 1960 or later), you likely have a valuable “conversion window.” Whether to use it depends on your current and future marginal tax rates, Medicare and ACA implications, state taxes, charitable plans, and estate goals.
What a Roth conversion actually solves
– Reduces future RMDs and the tax drag they create.
– Shifts growth into a tax-free account, which is especially powerful if you have a long horizon or higher-growth assets.
– Creates flexibility in retirement cash-flow (tax diversification).
– Improves after-tax outcomes for heirs (10-year rule on inherited IRAs makes Roth especially attractive).
– Mitigates the “widow(er)’s penalty” (survivors file as single with higher tax/IRMAA at lower income).
What it can worsen
– Raises current-year taxable income, potentially triggering higher brackets, Net Investment Income Tax (NIIT), loss of ACA subsidies, and future Medicare IRMAA surcharges (because IRMAA looks at MAGI from two years prior).
– Creates a near-term tax bill that must be funded (ideally from taxable cash, not the IRA).
– Is irrevocable—no recharacterizations for conversions.
Key variables to run before deciding
1) Your tax-rate arbitrage
– Compare your likely current marginal rate to your expected future marginal rate (include state taxes, IRMAA surcharges, NIIT, the Social Security taxation interaction, and the widow(er)’s penalty).
– If today’s all-in marginal rate is lower or similar to future years, a partial conversion often makes sense.
2) The conversion window
– Ages 63–75 are prime years: no RMDs yet, and you can control income. But:
– Before Medicare (generally until 65), conversions can cut ACA premium credits.
– After Medicare starts, conversions can increase Part B/D premiums two years later via IRMAA.
3) RMD pressure later
– If $1.2 million grows for 12 years, your first RMD at 75 could be substantial (the IRS factor at 75 is about 24.6). Even with moderate growth, RMDs can exceed typical spending needs, forcing taxable income you may not want.
– Converting some now trims future RMDs and the compounding tax drag.
4) Social Security timing
– Many retirees delay to 70 for higher benefits. Use the gap years to convert in chosen tax brackets.
– Once benefits start, your MAGI rises and IRMAA risk increases, making conversions more constrained.
5) Health insurance phase
– If you’re on ACA coverage at 63–64, conversions lift MAGI and can slash subsidies. Model this carefully; small conversions can be very expensive if they cross subsidy thresholds.
– At 63, your 2026 MAGI affects Medicare premiums at 65 (two-year lookback). Large conversions at 63 may trigger IRMAA at 65.
6) State taxes and domicile
– Converting while in a high-tax state is expensive; converting after a move to a low- or no-tax state is often better.
– Some states tax Roth conversions differently from IRA withdrawals; confirm current rules.
7) Charitable intent
– If you plan meaningful annual giving after 70½ via Qualified Charitable Distributions (QCDs), those can offset RMDs tax-efficiently—reducing the need to convert as much now.
– For legacy gifts, leaving pretax IRA assets to charity and Roth/taxable to heirs is usually optimal.
8) Heirs’ tax brackets and timelines
– Non-spouse heirs typically must empty inherited IRAs within 10 years. Inheriting a Roth gives them 10 years of tax-free growth and withdrawals. If heirs will be in high brackets, conversions tilt favorable.
9) Investment mix and horizon
– Conversions pay off more when you can house higher-growth assets in Roth for longer.
– Paying tax from taxable cash increases the effective amount moved into the tax-free side; paying tax from the IRA makes conversions less compelling.
10) Plan structure and special features
– Employer stock with low basis? Evaluate net unrealized appreciation (NUA) before rolling or converting.
– After-tax 401(k) subaccounts can often be isolated to Roth at very low tax cost; don’t miss that.
– In-plan Roth conversion vs. IRA conversion: functionally similar, but IRAs allow QCDs later.
A practical decision framework
– Step 1: Map your income from 63–80
– Pensions, interest, dividends, part-time work, rental income.
– Planned Social Security start date.
– Project balances and RMDs at 75+ under conservative, base, and optimistic return assumptions.
– Layer in state taxes, NIIT, IRMAA tiers, and likely deductions.
– Step 2: Identify annual “targets”
– Choose a top marginal rate you’re comfortable paying now (a line you’ll fill but not cross).
– Pre-Medicare years: decide how much ACA subsidy you’re willing to forgo, if applicable.
– Post-Medicare years: identify IRMAA cliffs you prefer to avoid.
– If married, consider converting more while you still file jointly to hedge the widow(er)’s penalty.
– Step 3: Execute partial conversions annually
– Convert late in the year when you have clearer income visibility.
– Fund the tax from taxable accounts if possible.
– Use safe-harbor estimated payments to avoid penalties.
– Reassess each year—markets, brackets, and personal circumstances change.
– Step 4: Asset location and withdrawal strategy
– Tilt higher expected-return assets to Roth, lower-yielding/safer assets to traditional.
– Keep some pretax IRA room for future QCDs if charitably inclined.
– Maintain liquidity in taxable accounts for tax bills and flexibility.
Rules and nuances to remember
– RMD age: 75 for those born in 1960 or later. No RMDs from Roth IRAs during your lifetime.
– Five-year rules: At 63, the 10% penalty on converted principal is irrelevant, but to withdraw Roth earnings tax-free you need to be 59½ and satisfy the 5-year clock since your first Roth IRA was opened. If you don’t already have a Roth IRA, open one to start the clock.
– IRMAA uses MAGI from two years prior. Today’s conversion can raise Medicare premiums two years from now.
– NIIT (3.8%) applies when MAGI exceeds statutory thresholds; conversions can push you over.
– Recharacterizations of conversions are no longer allowed—convert conservatively.
– If your 401(k) holds low-basis employer stock, evaluate NUA before rolling or converting—this can be a major tax saver.
When a conversion is usually a strong idea
– You have sizable pretax balances, expect similar or higher future tax rates, and can pay the tax from cash.
– You plan to delay Social Security and want to use the gap years to manage future RMDs.
– You’re married and want to hedge the widow(er)’s penalty by converting while MFJ brackets apply.
– You expect to leave assets to high-bracket heirs and want to maximize tax-free bequests.
When to hold back or be very selective
– You’re on ACA coverage and value the premium credits at 63–64.
– You’ll soon move to a much lower-tax state.
– You expect large future deductions (e.g., long-term care costs) that could absorb RMDs.
– You intend to do substantial QCDs after 70½ or leave the IRA to charity.
– You have NUA opportunities on employer stock that should be handled first.
A quick, CPA-friendly way to set your 2026 target
– Build a one-page “tax map” for 2026–2038 with:
– Base-case MAGI each year with no conversions.
– The top-of-target-bracket/IRMAA/NIIT thresholds you’re willing to hit.
– Annual conversion amount = threshold minus projected ordinary income (adjust for ACA/IRMAA).
– Run three scenarios (no conversion, stair-step conversions, front-loaded conversions) and compare:
– Lifetime taxes paid (federal + state + IRMAA).
– After-tax net worth at, say, age 85–90.
– After-tax inheritance to heirs under the 10-year rule.
Bottom line
With $1.2 million in a 401(k) and a long runway before RMDs, partial Roth conversions often pay—especially if you can use the pre-RMD years to fill lower tax brackets without tripping costly cliffs. The biggest pitfalls at 63 are ACA subsidies now and IRMAA later. If those don’t dominate—and you can fund the tax from cash—an annual, bracket-aware conversion plan is likely to reduce future RMDs, improve tax diversification, and enhance what your heirs keep.
Build a 10–15 year tax map, set annual thresholds, and convert steadily. Revisit each year as markets, laws, and your life evolve.
