The Low-Income Window: Using Social Security Delay and Fixed Income Tactics to Maximize Roth Conversions

Understanding the Low-Income Window

Consider a typical retirement timeline: a couple retires at 62–65 with no wages. They have not yet started Social Security. Their RMDs do not begin until age 73. During this gap — which can span 5–10 years — they have little or no mandatory income. Their taxable income is largely within their control.

This is the low-income window. It may be the only period in their adult lives when they can choose to recognize significant taxable income at low marginal rates — and pay taxes at 12% or 22% on dollars that, if left alone, will be forced out as RMDs at 24%, 32%, or higher once Social Security, RMDs, and potentially a spouse's income compound together in their 70s and 80s.

Why Social Security Delay Amplifies This Window

Delaying Social Security to age 70 earns 8% per year in Delayed Retirement Credits. But there is a second benefit that is often overlooked: it extends the low-income window. If you claim Social Security at 62, you receive benefits immediately — and those benefits begin pushing your MAGI up right away (up to 85% of Social Security is taxable). Delaying to 70 keeps Social Security income off your tax return for up to 8 additional years.

Those 8 years are 8 more years of low-income Roth conversion capacity. The delay pays off twice: a permanently higher inflation-adjusted benefit starting at 70, and 8 years of wider Roth conversion space before that income begins.

The Fixed Income Bucket: Funding Life While Converting

The challenge of the low-income window is that you still need to pay living expenses while you are actively converting IRA assets to Roth. The conversion itself is taxable income — you cannot also take large IRA withdrawals for living expenses without pushing MAGI above the target bracket. The solution is a separate "fixed income bucket" of liquid, low-tax assets you can live off while the conversion happens.

What Goes in the Fixed Income Bucket

• Roth IRA balances (previously contributed or converted): Qualified Roth distributions have zero MAGI impact. Drawing from Roth accounts for living expenses leaves the entire conversion space open for IRA-to-Roth transfers.
• After-tax taxable brokerage accounts: Selling assets with low or zero capital gains (basis close to market value) generates minimal taxable income. Assets held long-term and sold at the 0% long-term capital gains rate (available up to ~$94,000 MAGI for a couple in 2025) have essentially no tax cost.
• Cash and savings: Using savings accumulated before retirement — with no tax consequence — funds living expenses without affecting MAGI.
• I-Bonds or TIPS: Treasury Inflation-Protected Securities held to maturity or I-Bonds offer a tax-deferred interest option; interest is recognized only when redeemed, giving some control over timing.
• MYGA or CD maturities: Interest from CDs or MYGAs maturing during the window is taxable, but can be planned around.

What to Avoid Drawing From in the Window

• Traditional IRA beyond the conversion target: Extra withdrawals beyond what you intend to convert push MAGI higher without creating a Roth balance. Use the bucket instead.
• Large taxable stock sales: Recognizing large capital gains competes with conversion capacity in the same MAGI budget.

Bracket Filling: How to Size the Annual Conversion

The goal is to fill the current tax bracket to the top each year without crossing into the next bracket — and to respect IRMAA thresholds two years forward. This requires knowing your "conversion capacity" annually: the gap between your current MAGI and the top of your target bracket, after accounting for all other income sources.

Step-by-Step Annual Calculation

• Step 1: Estimate all non-conversion taxable income: dividends, interest, rental income, part-time work income, and any Social Security that is taxable (85% of benefits).
• Step 2: Subtract your standard deduction (or itemized deductions) to determine your current taxable income before any conversion.
• Step 3: Identify the top of your target bracket (e.g., 22% bracket for married filing jointly ends at $201,050 of taxable income in 2025).
• Step 4: The difference between current taxable income (Step 2) and the bracket ceiling (Step 3) is your conversion capacity.
• Step 5: Check IRMAA: your MAGI two years from now must stay below the first IRMAA threshold ($106,000 single / $212,000 joint) — or at least not cross an additional tier beyond what you've already planned for.
• Step 6: Execute the conversion amount from Step 4 (adjusted for IRMAA if needed), pay the tax from non-IRA funds if possible.

The Full Strategy Timeline: A Case Study

• Ages 62–66: The Core Conversion Window Zero Social Security income. No RMDs. Standard deduction ~$30,000 (married filing jointly). Taxable income before conversion: ~$15,000 (dividends + interest). Conversion capacity to top of 22% bracket: approximately $186,000/year. After IRMAA check (target MAGI below $212,000 joint), they convert $175,000–$185,000 annually. Tax paid from brokerage account (rebalancing low-basis stock over time). After 5 years: ~$900,000 moved to Roth at 12–22% rates.
• Ages 67–69: Susan Claims SSA; Conversion Continues Susan files at 67 for her own benefit (~$1,400/month). Approximately 85% is taxable: ~$14,280/year additional income. Conversion capacity narrows slightly but remains substantial. Robert continues delaying to 70. Annual conversion reduced to approximately $155,000 to stay within IRMAA bounds.
• Age 70: Robert Claims SSA Robert's benefit at 70: $3,200 × 124% = $3,968/month (~$47,616/year). 85% taxable: ~$40,474/year. Combined Social Security taxable income: ~$54,754/year. This sharply reduces conversion headroom. Future conversions must be sized carefully against the combined income stack.
• Ages 73+: RMDs Begin RMDs on the now-reduced traditional IRA balance (significantly smaller due to years of conversion) are manageable — perhaps $45,000/year instead of $90,000+ on the original balance. Combined with Social Security, total taxable income is roughly $100,000 — still below the 22% bracket ceiling and below the first IRMAA threshold.

The 0% Capital Gains Opportunity Within the Window

A related tactic often missed alongside Roth conversions: realizing long-term capital gains at the 0% federal rate. For 2025, the 0% rate applies to long-term gains when total taxable income is below approximately $94,050 (married filing jointly). In the early years of the low-income window — before a large portion of the bracket is consumed by conversions — there may be room to also harvest capital gains from taxable accounts at zero tax cost.

Running this in parallel with Roth conversions requires careful MAGI management, as both conversions and capital gains consume bracket space. But in a year with particularly low other income, converting to the top of the 12% bracket while simultaneously realizing gains at 0% is entirely possible with precise planning.

IRMAA Coordination: The Two-Year Forward Look

Every conversion decision you make today sets your Medicare premium two years from now. If Medicare coverage has already started (or starts within two years), IRMAA must be layered into the annual conversion sizing calculation. The target is not simply "fill the bracket" — it is "fill the bracket up to the IRMAA cliff that matters most."

For most couples who are Medicare-eligible, staying below $212,000 MAGI preserves the standard Part B premium. If crossing to the first tier is unavoidable because of RMD size, Social Security income, or large gains, convert to the top of that tier rather than just barely over — extract maximum Roth benefit from paying that tier's premium once.

The Impact on Heirs: The "Empty Roth" Inheritance

A fully converted Roth IRA passed to heirs is dramatically more valuable than an equivalent traditional IRA. Under the SECURE Act 2.0, most non-spouse beneficiaries must empty inherited IRAs within 10 years. A $1 million inherited traditional IRA forces a beneficiary — potentially in their peak earning years — to recognize $1 million in taxable income over 10 years, possibly at 32–37% marginal rates.

The same $1 million in an inherited Roth IRA: zero taxes on distributions, and 10 years of tax-free growth before the balance must be withdrawn. The pre-payment of taxes during the low-income window at 12–22% — instead of the beneficiary paying 32–37% — is a permanent, multi-generational tax arbitrage.