Retirement Withdrawal Strategy for Couples: Sequencing, the Roth Conversion Window, and the IRMAA Cliff

Most retirement withdrawal advice is written for one person. Couples have two sets of accounts, two ages, two Social Security benefits, and two RMD timelines — and that changes almost every calculation. This guide covers the decumulation decisions that matter most.

The withdrawal order baseline — and why it's more nuanced for couples

The standard advice: draw down accounts in this order — taxable brokerage first, traditional pre-tax accounts (401(k), IRA) second, Roth accounts last. The logic is to let tax-advantaged growth compound as long as possible and defer taxation until forced.

For couples, the calculus is more complex:

• Account asymmetry. It's common for one spouse to have most of the traditional IRA/401(k) balance while the other holds most of the Roth. The optimal sequence depends on who owns what — not just what account types exist.
• Two separate RMD clocks. If spouses are different ages, one triggers required distributions before the other. The age gap creates planning opportunities if addressed years ahead of time.
• The survivor scenario shapes all of it. At first death, one Social Security benefit disappears and the surviving spouse shifts from married-filing-jointly to single tax brackets. Decisions made today have compounding consequences for whoever lives longer.

The standard sequence is a starting point. What overrides it: the Roth conversion window, IRMAA management, and the size imbalance between each spouse's traditional accounts.

Your Roth conversion window: the years between retirement and RMDs

The most valuable planning window many couples miss is the gap between the day you stop earning W-2 income and the day your required minimum distributions begin. Under SECURE 2.0,¹ RMDs start at age 73 for those born 1951–1959, and age 75 for those born 1960 or later. Retire at 62 with an RMD start date of 75 and you have 13 years when your taxable income is substantially lower than it was while working — and potentially lower than it will be once RMDs force large distributions.

That window is your opportunity to convert traditional IRA and 401(k) balances to Roth at favorable rates.

Concrete example: A couple with $2 million in a traditional IRA who retires at 63 might have $45,000–$60,000 in combined Social Security income plus modest dividends — total MAGI well under $200,000. Converting $100,000–$130,000/year to Roth fills the top of the 22% bracket now, before RMDs potentially push that same income into the 24% or 32% bracket. The break-even is typically 5–8 years depending on your state and rate assumptions, with lifetime tax savings often exceeding $100,000 for a couple in this situation.

What complicates the window for couples

• Staggered retirement. If one spouse is still earning income, their wages fill the lower brackets first, reducing or eliminating room to convert at low rates. The window often doesn't fully open until both spouses are retired.
• ACA marketplace coverage. If you retire before 65 and need Marketplace health insurance, Roth conversions count as MAGI and can phase out premium tax credits. Some couples deliberately limit conversions in pre-Medicare years for this reason.
• IRMAA lag. Conversions today affect Medicare premiums two years later. A $150K conversion in 2024 that pushes MAGI to $250,000 triggers Tier 2 IRMAA surcharges in 2026 — an extra cost that must be factored into the conversion math.

The IRMAA cliff: why $1 over the threshold costs $2,000/year for the couple

IRMAA (Income-Related Monthly Adjustment Amount) is a Medicare surcharge applied to beneficiaries whose MAGI exceeds a threshold. The surcharge is not a percentage — it's a cliff: one dollar over the tier boundary triggers the full surcharge for that tier, for both enrollees.

In 2026, the Tier 1 threshold for married couples filing jointly is $218,000 MAGI based on your 2024 tax return.² Cross it by $1 and each enrolled spouse pays an additional $81.20/month for Part B, on top of the standard 2026 premium of $202.90/month.³ For a couple where both spouses are on Medicare: $162.40/month extra, or approximately $1,949/year combined. Higher tiers escalate further, with total Part B premiums ranging from $284.10 to $689.90/month per enrollee across all tiers.

What counts as MAGI for IRMAA

IRMAA MAGI is broad: wages, dividends, capital gains, Roth conversion amounts, interest, rental income, and taxable Social Security income all count. A $100,000 Roth conversion doesn't just raise your current-year income tax — it creates an IRMAA surcharge two years later for both spouses. Neither spouse sees a bill from Medicare; the surcharge is deducted directly from Social Security payments, which makes it easy to miss in planning.

The practical planning rule

Before executing any Roth conversion, project your MAGI for that tax year and check it against the IRMAA Tier 1 threshold. For most couples, the optimal Roth conversion target each year is "as much as possible without crossing $218,000 MAGI." Converting an extra $20,000 above the tier boundary doesn't just cost the income tax on that $20,000 — it also triggers the Tier 1 IRMAA surcharge for both spouses two years out. In many scenarios, that total cost makes the marginal conversion not worth it.

The math changes once you cross into higher tiers deliberately — at that point you might as well convert more while you're already in the tier. The goal is to avoid being $1 over a tier boundary.

Harvesting capital gains at 0%

Long-term capital gains are taxed at 0% for couples with taxable income below $98,900 in 2026.⁴ During the Roth conversion window, a couple with modest income (partially-taxable Social Security, some dividends, no wages) may have significant room below that threshold — room to sell appreciated brokerage positions and pay zero federal tax on the gain.

The mechanics of tax-gain harvesting: sell the appreciated position, pay 0% on the realized gain, immediately repurchase at the new (higher) cost basis. Future gains are deferred from the reset basis. Combined with Roth conversions, a couple can meaningfully reduce both the taxable portion of their portfolio and their future capital gains exposure over the pre-RMD window.

The IRMAA interaction applies here too. Capital gains count toward MAGI. Managing Roth conversions and capital gain harvesting in the same year requires a combined MAGI projection — it's easy to underestimate how quickly they stack.

RMD coordination: two spouses, two ages, two timelines

Each spouse's RMDs are calculated independently. Each year's required distribution is the account balance divided by the IRS Uniform Lifetime Table divisor for that spouse's age — there is no joint calculation. This means couples have real flexibility in how they sequence drawdowns before RMDs begin.

Key coordination decisions

• Which spouse's traditional accounts are larger? If Spouse A has $1.8M in traditional accounts and Spouse B has $400K, Spouse A's future RMDs will be large regardless of Spouse B's choices. The Roth conversion strategy should prioritize converting Spouse A's balance — even if that makes Spouse A's Roth much larger than Spouse B's.
• Age gap matters. If one spouse is 10 years older, their RMDs may begin while the other is still working. That stacks forced distributions on top of earned income in high-bracket years — exactly the wrong sequence. Identifying this early and converting more aggressively from the older spouse's accounts is often the single best move.
• Roth 401(k) accounts now have no lifetime RMD requirement. Starting in 2024, Roth 401(k) and Roth TSP accounts are treated the same as Roth IRAs — no required distributions during the owner's lifetime.⁵ If you have Roth money in a former employer's 401(k) that you haven't rolled over, it's worth doing — the money grows forever without forcing a distribution.

Social Security as the longevity anchor

For most couples, Social Security is the single largest financial decision in the retirement income plan. The survivor-optimized strategy is asymmetric: the lower earner claims early to reduce the portfolio draw during the delay period, while the higher earner delays to 70 to lock in the maximum survivor benefit.

At first death, the smaller SS benefit disappears. The surviving spouse receives the larger of the two. Delaying the higher earner's benefit to 70 increases it approximately 32% over FRA — and that larger amount is what the survivor lives on, potentially for 20–30 years. For couples where the earnings history is asymmetric, this decision often increases lifetime household Social Security income by $200,000–$400,000 compared to both claiming at 62.

The portfolio bridges the delay period: if the higher earner delays to 70 and retires at 65, you need five years of bridge income from the portfolio (or the lower earner's early SS plus savings). That bridge cost is real — but weighed against decades of higher survivor income, most couples find delaying the higher-earner benefit to be the highest-ROI decision in the entire plan.

See our Social Security guide for couples for the full spousal and survivor benefit analysis, including the break-even math.

The widower's trap: modeling the survivor scenario now

This is the scenario most couples underplan for — and the one where decisions made during the joint-filing years matter most.

At first death:

1. One Social Security benefit disappears. The smaller check stops. Combined SS income drops by 30–40% for most couples — while most fixed expenses (housing, insurance, utilities) remain unchanged.
2. Tax brackets compress immediately. The surviving spouse files as single. Single bracket thresholds are roughly half of MFJ thresholds. RMD income that landed in the 22% bracket jointly may now fall in the 32% bracket as a single filer.
3. IRMAA thresholds halve. The single-filer IRMAA Tier 1 threshold is $109,000 — exactly half the MFJ threshold. RMD income that stayed under the couples IRMAA floor may now trigger surcharges for the surviving spouse every year for the rest of their life.
4. Survivor spending doesn't halve. Research consistently shows survivor spending runs 70–80% of joint spending. SS income typically falls more than spending, creating a persistent income gap.

The planning implication: Roth conversions during the joint-filing window serve a dual purpose. They reduce your tax bill now — and they reduce the RMD burden the survivor faces decades later in compressed single brackets. This is often the most compelling argument for maximizing conversions up to the IRMAA threshold every year during the window, rather than spreading them out conservatively.

Putting it together: the annual conversion window checklist

For a couple that recently retired with most savings in traditional accounts:

1. Project MAGI for the year. Start with income that's already locked in: dividends, interest, capital gain distributions, Social Security (once claimed), rental income. What's your floor without any conversions?
2. Identify fill-up room. How much space remains between your income floor and (a) the top of your current tax bracket and (b) the IRMAA Tier 1 threshold ($218K MFJ MAGI for 2026)?
3. Layer in a Roth conversion to fill that room. Prioritize converting the higher-balance spouse's traditional accounts. Stop before crossing IRMAA Tier 1 unless the marginal amount is large enough to justify voluntarily entering the tier (and finishing the tier).
4. Check 0% capital gains room. After accounting for Roth conversions, verify whether you have room below the $98,900 taxable-income threshold. If yes, harvest gains in taxable accounts to reset your cost basis tax-free.
5. Model the survivor scenario. For the same conversion amount, rerun the projection assuming only the surviving spouse's income and using single brackets. Does the conversion strategy still make sense?
6. Reproject every year. Tax law changes. SS timing changes. Spending changes. This is not a one-time analysis.

Sources

1. IRS — Required Minimum Distributions FAQs. SECURE 2.0 Act § 107: RMD age is 73 for those born 1951–1959 and 75 for those born 1960 or later.
2. SSA POMS HI 01101.020 — 2026 IRMAA Sliding Scale Tables. 2026 IRMAA Tier 1 threshold: $218,000 MAGI for married filing jointly (based on 2024 tax return).
3. CMS — 2026 Medicare Parts A & B Premiums and Deductibles. Standard Part B premium: $202.90/month. IRMAA Tier 1 monthly Part B premium: $284.10. Full IRMAA range: $284.10–$689.90/month per enrollee.
4. IRS — 2026 Tax Inflation Adjustments. 0% long-term capital gains rate applies to MFJ taxable income up to $98,900 for 2026.
5. Fidelity — SECURE 2.0 Roth 401(k) RMD Rule Change. SECURE 2.0 § 325: Roth 401(k) and Roth TSP accounts have no lifetime RMD requirement starting 2024, matching Roth IRA treatment.

IRMAA figures reflect 2026 premiums based on 2024 MAGI per SSA POMS and CMS published rates. Capital gains threshold from IRS 2026 inflation adjustments. RMD ages per SECURE 2.0 Act. Values verified April 2026. This page provides general educational information, not tax or investment advice specific to your situation.