Roth Conversion at 68 or 69: The Peak Window Before Social Security Starts

For retirees who delayed Social Security to age 70, ages 68 and 69 represent the highest-capacity Roth conversion window in their entire retirement. There's no Social Security income pulling income up toward higher brackets, no required minimum distributions for another 4–5 years, and Medicare is fully established — so there are no surprises left in the IRMAA picture. If your only taxable income is dividends and interest, the standard deduction may cover it entirely, leaving the entire conversion running from zero through the 12% and 22% brackets at an effective rate of 14–17%.

This guide covers what's specifically useful at 68–69: the dramatic difference between conversions with and without SS income, the IRMAA timing nuance (what you convert now shows up in your Medicare bill the year SS starts), and how to size the two remaining years of maximum conversion capacity before the picture changes at 70.

Who this guide is for

Under SECURE 2.0 Act § 107, RMD age is 73 for those born 1951–1959 and 75 for those born 1960 or later.¹ The 68–69 window is most relevant for the 1957–1958 birth cohort (turning 68 or 69 in 2026), who face RMD age 73 — giving them 4–5 years of pre-RMD conversion runway remaining.

RMD age per SECURE 2.0 § 107. Those born 1960 or later have RMD age 75, giving them additional runway; the math below still applies.

The two paths at 68–69

Your conversion picture looks dramatically different depending on whether Social Security has started:

• Path A — SS still delayed (most powerful): No SS income. Your taxable income floor is near zero — likely just dividends, interest, and any part-time work. The standard deduction ($35,500 for a couple both 65+) often wipes out all non-conversion income, leaving the full 12% and then 22% brackets available for conversions. IRMAA Tier 1 ($218,000 MAGI for MFJ) is the binding ceiling.
• Path B — SS already started: SS income (typically 85% taxable) fills your lower brackets before any conversion. You still have meaningful conversion room — but roughly $60,000–$80,000 less per year than Path A, and the SS torpedo interaction increases your effective marginal rate in the phase-in zones.

If you're on Path B, the math is essentially the same as the age 70–72 guide, just applied earlier. The rest of this guide focuses on Path A — the SS-delayed scenario — because it's the situation where being 68 or 69 creates a uniquely favorable window.

Path A: conversion capacity with SS delayed

The income floor calculation

For a couple both 68–69 with no SS income, typical retirement income sources are:

• Dividends and interest from taxable accounts
• Pension or annuity income (if any)
• Part-time consulting or self-employment
• Inherited IRA distributions (if taking them)

For a couple with no pension and modest investment income ($12,000–$18,000/year), the 2026 standard deduction for married filing jointly with both spouses age 65+ is $35,500 ($32,200 base + $1,650 each for age 65+).² That deduction covers most or all of the non-conversion income — leaving virtually the entire conversion running from the bottom of the tax bracket table.

How much can you convert?

For this scenario, IRMAA Tier 1 is the operative ceiling, not the bracket ceiling. The 2026 Tier 1 threshold is $218,000 MAGI for married filing jointly.³ Your maximum conversion is $218,000 minus all other income (wages, dividends, interest, pension — but not the standard deduction, since MAGI is pre-deduction).

Rates estimated using 2026 MFJ brackets (12% through $100,800, 22% through $211,400 taxable income). IRMAA Tier 1 MFJ threshold: $218,000 MAGI per CMS 2026 fact sheet. Actual effective rate depends on itemized deductions, state tax, and LTCG stacking.

Path A vs. Path B: the conversion room gap

Here's how much the SS delay extends conversion capacity:

Delaying SS to 70 creates roughly $40,000–$72,000 more annual Roth conversion capacity compared to claiming SS at 66–67. Over two years (ages 68 and 69), that's up to $144,000 in additional conversions. At a 22% rate now versus a likely 32% marginal rate later when RMDs stack on SS, the tax differential is roughly $14,400 in lifetime savings from just that extra capacity — per year, per year of RMDs thereafter.

Worked example: Laura and Michael, both 68

Laura (68) and Michael (68), both born 1958. Both chose to delay Social Security to age 70 — SS starts in 2028, when they'll be 70. Michael has a $1.9 million traditional IRA. Laura has $280,000 in a traditional IRA. They have $14,400/year in dividends from a taxable brokerage account. No pension. Both fully on Medicare (Part A, B, D) since age 65.

RMD deadline for both: RMD age 73 = 2031. Five pre-RMD years remain, including 2026 and 2027 before SS starts, then 2028–2030 with SS income.

Non-conversion taxable income (2026):

• SS income: $0
• Dividends: $14,400
• Standard deduction (MFJ, both 65+): $35,500
• Taxable income before conversion: $14,400 − $35,500 = $0 (standard deduction covers all income)

IRMAA ceiling (2026):

• IRMAA Tier 1 MAGI threshold (MFJ): $218,000
• Other income: $14,400
• Max conversion to stay under Tier 1: $218,000 − $14,400 = $203,600

They decide to convert $200,000 from Michael's IRA to a Roth IRA in 2026.

Federal tax on the conversion:

• Taxable income after conversion: $200,000 (full conversion is taxable, standard deduction already absorbed dividends)
• First $100,800 at 12%: $12,096
• Next $99,200 at 22%: $21,824
• Total federal tax: ~$33,900
• Effective rate on conversion: ~16.9%

They pay these taxes from their taxable brokerage account — not withholding from the conversion itself, which would reduce the amount transferred to Roth and compound the penalty.

Year 2 (2027, age 69): Similar capacity — $14,400 dividends, no SS. Michael's IRA has grown to approximately $1,807,000 (($1.9M − $200K) × 1.065). They convert another $200,000 at ~16.9%.

At age 70 (2028), when SS starts: Michael's IRA has grown to ~$1,715,000 (($1,807K − $200K) × 1.065). Their combined SS at maximum-delayed rates is approximately $78,000/year. Annual conversion room under IRMAA Tier 1 drops to about $126,600. They've moved $400,000 to Roth in the two highest-capacity years.

RMD impact at 73 (2031): Using the IRS Uniform Lifetime Table divisor of 26.5 at age 73:⁴

• Without the $400K conversion: IRA grows ~$1.9M × 1.065⁵ = ~$2,588,000. Year-1 RMD = $2,588,000 ÷ 26.5 = $97,660
• With the $400K conversion: IRA ≈ $1,715,000 in 2028, continues growing to ~$1,715,000 × 1.065³ = ~$2,075,000 by 2031. Year-1 RMD = $2,075,000 ÷ 26.5 = $78,300
• Annual RMD reduction: ~$19,360/year

That $19,360 RMD reduction at 32% marginal rate saves about $6,195 per year in taxes — every year throughout retirement. The $400K in Roth also grows tax-free for Michael's and Laura's heirs, compared to the inherited IRA 10-year mandatory withdrawal schedule they would otherwise receive.

The IRMAA timing nuance at 68–69

At ages 68 and 69, the IRMAA lookback lands in a particularly interesting year: what you convert in 2026 (age 68) determines your 2028 Medicare premiums — the year you turn 70 and Social Security begins.

This means two high-income events can stack: (1) the 2026 conversion shows up as a 2028 IRMAA surcharge, and (2) starting SS in 2028 adds new income that also triggers IRMAA from that point forward. For Laura and Michael:

• 2026 conversion MAGI: $214,400 → 2028 IRMAA: Tier 1 triggered ($1,148/person/year couple = $2,296/year)
• 2027 conversion MAGI: $214,400 → 2029 IRMAA: Tier 1 again ($2,296/year)
• 2028 SS income alone: ~$78,000 → 2030 IRMAA depends on actual 2030 thresholds

The 2028 IRMAA cost from the 2026 conversion is a one-year surcharge ($2,296 for a couple). The lifetime tax savings from converting $200,000 at 17% rather than 32%+ are on the order of $30,000. The IRMAA cost is about 8% of the lifetime savings — easily worth it.

Coordinating with the 5-year pre-RMD runway

For the 1958 cohort (RMD age 73, first RMD in 2031), the 5-year pre-RMD runway breaks into two distinct phases:

Estimates based on $78K combined SS at 70 (delayed to max), $14,400 other income, MFJ, no pension, 2026 thresholds. Actual amounts will vary with IRA growth and future-year IRMAA threshold adjustments.

The two pre-SS years (2026–2027) offer approximately $200,000/year in capacity; the three post-SS years (2028–2030) offer roughly $130,000–$140,000. Total 5-year potential: approximately $790,000–$820,000 of conversions, with $400,000 of that front-loaded into the best-rate window.

If a large traditional IRA makes converting the full $800K+ infeasible in 5 years, front-loading years 1–2 maximizes the low-rate advantage. The goal isn't necessarily to drain the IRA — it's to reduce the RMD trajectory enough to prevent bracket creep and widow-bracket exposure over a 20+ year retirement.

The widow bracket consideration

For married couples at 68–69, the widow bracket risk is still a planning priority. When one spouse dies, the survivor files as Single — with brackets that are approximately half the width of MFJ but income that doesn't drop by half. A surviving spouse with a $1.5M IRA, $40,000 in SS, and a year-1 RMD of ~$56,600 at age 73 faces:

• SS taxability: 85% of $40K = $34,000 taxable SS
• RMD: $56,600
• Total AGI: $90,600
• After single-filer standard deduction ($18,150 at 65+): taxable income = $72,450
• Single-filer 22% bracket ceiling: $105,700 (2026). That $72,450 taxable income sits squarely in the 22% bracket — but approaching the top. Add any investment income and the 24% bracket becomes possible.

Converting aggressively at 68–69 while both spouses are alive and using the full MFJ brackets is the most direct way to protect the surviving spouse from this scenario. Every $100,000 moved to Roth now is $100,000 that won't appear as a forced single-filer RMD in later years.

Frequently asked questions

I'm 68 and already on Social Security — does this guide still apply?

The Path A math (no SS) won't match your situation. With SS income, your conversion ceiling under IRMAA Tier 1 is roughly $40,000–$80,000 lower depending on your SS benefit. The mechanics, timing, and widow bracket considerations still apply; the amounts are just smaller. See the age 70–72 guide for the math with SS already running.

Can I convert if I'm still working at 68?

Yes. There's no rule preventing Roth conversions while working. However, W-2 income adds directly to your MAGI and reduces the conversion room under IRMAA Tier 1. A couple where one spouse earns $60,000 in consulting income has about $140,000 of IRMAA headroom instead of $200,000. The working and converting guide covers the interaction between earned income and conversion capacity, including the super catch-up contribution strategy for ages 60–63 that may still apply.

Should I cross the IRMAA Tier 1 threshold at 68?

Often yes, if the conversion savings are large relative to the surcharge. The Tier 1 surcharge for 2028 (when the 2026 IRMAA lookback lands) is $1,148/person/year — $2,296 for a couple. If crossing Tier 1 allows an additional $50,000 conversion at 22% versus a likely 32% future rate, the tax differential is $5,000 and the IRMAA cost is recovered in under 6 months of RMD savings. The IRMAA guide covers the full tier-crossing break-even analysis.

What's the deadline for Roth conversions?

December 31 of the tax year. A 2026 conversion must be processed and settled by December 31, 2026 — unlike IRA contributions, which can be made until the April 15 filing deadline. The conversion deadline guide covers custodian processing cutoffs and the December tax-withholding adjustment option for paying the tax bill.

Is converting at 68–69 worth it if my IRA is smaller — say $400K?

The same logic applies at smaller balances, but the conversion amounts that make sense are smaller. A $400K IRA at age 68 generates a first-year RMD of roughly $15,000 at age 73. Even one year of converting $80,000–$100,000 in the no-SS window can reduce the RMD trajectory meaningfully and protect a surviving spouse. The lifetime savings are smaller in absolute terms but the math — converting at 12–17% now to avoid 22–32% later — still holds.

Sources

1. IRS: Retirement Topics — Required Minimum Distributions (RMDs) — confirms RMD age is 73 for those born 1951–1959 and 75 for those born 1960 or later under SECURE 2.0 Act § 107.
2. IRS Rev. Proc. 2025-32 — 2026 federal income tax brackets and standard deduction amounts. Standard deduction MFJ: $32,200. Additional standard deduction age 65+: $1,650/qualifying individual (MFJ). Combined for couple both 65+: $35,500. 12% bracket MFJ ceiling: $100,800. 22% bracket MFJ ceiling: $211,400.
3. CMS: 2026 Medicare Parts B and D Income-Related Monthly Adjustment Amounts — 2026 IRMAA Tier 1 MAGI threshold: $218,001 for married filing jointly (based on 2024 MAGI). Per-person annual Part B + Part D Tier 1 surcharge: approximately $1,148/year ($81.20/mo Part B + $14.50/mo Part D). Couple cost: ~$2,296/year.
4. IRS Publication 590-B — Uniform Lifetime Table (T.D. 9930, effective 2022) — RMD divisors. Age 73: 26.5. Age 74: 25.5. Age 75: 24.6. No change from 2022 update for 2026 purposes.

RMD age per SECURE 2.0 Act § 107. IRMAA thresholds from CMS 2026 fact sheet; IRMAA is based on MAGI from two years prior. Tax brackets and standard deduction from IRS Rev. Proc. 2025-32. SS taxability thresholds per IRC § 86 (unchanged since 1993). ULT divisors from IRS Pub. 590-B (T.D. 9930). Worked example uses 6.5% assumed IRA growth; actual results vary. Values verified June 2026.