Roth Conversion with Pension Income: How a Guaranteed Income Floor Reshapes Your Conversion Window

A pension doesn't disqualify you from Roth conversions — but it does change the math significantly. Because pension income is taxed as ordinary income, it fills your lower tax brackets before you convert a single dollar. The result: less room at 12%, less room at 22%, and an IRMAA threshold that may arrive sooner than you expect. Understanding this compression is the first step to a sensible conversion plan.

The core problem: pension income occupies your brackets first

The Roth conversion "golden window" exists because retiring creates a temporary gap in your taxable income — earned income has stopped, Social Security may not have started, and RMDs don't begin until age 73 or 75. In that gap, brackets that were previously filled with wages are now empty, creating room for low-rate conversions.

A pension partially closes that gap. Your pension is taxable as ordinary income at the federal level — the same income type as wages and traditional IRA withdrawals.¹ It occupies the same brackets from the bottom up, before any conversion dollar enters the picture.

The practical effect: a retiree with a $70,000 pension and no other income has already filled roughly $34,500 of taxable capacity (after the MFJ standard deduction) before converting anything. That's money that would otherwise be "free bracket room" for low-rate conversions.

Calculating your available conversion room

The formula is the same regardless of income source:

Taxable income before conversion = Pension income − Standard deduction (+ other income, if any)

Conversion room = Bracket ceiling − Taxable income before conversion

2026 federal bracket ceilings (MFJ, taxable income):²

Standard deduction 2026: $32,200 MFJ / $16,100 single. Add $1,650 per qualifying person age 65+ (MFJ) or $2,050 (single) — so a MFJ couple both age 66 gets $35,500 combined.

Quick-reference: how much you can convert at 22% or below by annual pension amount (MFJ, both age 66, no other income):

Pension income shrinks the window but doesn't eliminate it. A couple with a $100,000 combined pension still has nearly $147,000 of room at 22% or below — meaningful for a large IRA.

Worked example: Patricia and Robert, ages 66 and 65

Patricia is a retired public school teacher in her second year of retirement. Her CalSTRS pension is $52,000/year. Robert retired from federal service under FERS; his annuity is $38,000/year. Combined pension income: $90,000.

They hold $1.1 million in traditional IRA accounts (primarily rolled over from Robert's TSP). They are both delaying Social Security to age 70. They have no earned income.

Standard deduction: $32,200 (MFJ base) + $1,650 (Patricia, age 66) + $1,650 (Robert, age 65 — qualifies for 65+ addition) = $35,500

Taxable income before conversion: $90,000 − $35,500 = $54,500 (solidly in the 12% bracket, which runs to $100,800)

Their conversion room by bracket target:

• Fill 12% bracket: $100,800 − $54,500 = $46,300 — tax cost ~$5,900 (~12.7% average on conversion)
• Fill 22% bracket: $211,400 − $54,500 = $156,900 — everything above $46,300 is taxed at 22%
• Fill 24% bracket: $403,550 − $54,500 = $349,050 — substantial, but IRMAA intervenes first (see below)

IRMAA: pension income counts toward the same MAGI threshold

Medicare IRMAA surcharges are based on your MAGI (modified adjusted gross income), not taxable income. Your pension income counts fully toward MAGI — which means you're starting closer to the IRMAA thresholds before you convert anything.³

2026 IRMAA thresholds (MFJ): Tier 1 begins at $218,000 MAGI. For Patricia and Robert:

• MAGI before conversion: ~$90,000 (pension income)
• IRMAA Tier 1 headroom: $218,000 − $90,000 = $128,000 of conversion room before the first IRMAA surcharge

The bracket math said they could convert $156,900 to fill the 22% bracket — but IRMAA clips that at $128,000. Converting the full $156,900 would push MAGI to $246,900, crossing IRMAA Tier 1 ($218,000) and triggering roughly $1,943/year in added Medicare Part B and Part D premiums for two years (based on 2026 Tier 1 surcharge rates).

In practice, a pension holder's IRMAA ceiling often binds before the bracket ceiling does. For this couple, the practical annual conversion limit — staying below IRMAA Tier 1 — is $128,000, not $156,900.

The IRMAA two-year lookback means 2026 conversions affect 2028 Medicare premiums. Factor this into multi-year planning rather than year-by-year optimization.

Why Roth conversion still makes very good sense with a pension: the RMD pile-up

It might seem like a pension argues against conversions — your brackets are already partially occupied. But look at what happens at RMD age if you don't convert.

Patricia and Robert's $1.1M IRA, growing at 6% over 9 years until Robert's RMD age at 75: approximately $1.86 million. Year-1 RMD using the IRS Uniform Lifetime Table divisor of 22.9 at age 75: roughly $81,200.⁴

Their taxable income at 75 without any prior conversions:

• Pension: $90,000
• RMD: $81,200 (grows each year as IRA balance persists)
• Social Security (assumed claimed at 70): ~$65,000/year combined, 85% taxable = $55,250
• Gross income: $226,450 → Taxable income: ~$190,950 (after standard deduction)

That's solidly in the 22% bracket — with no room left to do any future conversion at lower rates. And RMDs grow every year as the IRA grows faster than they can withdraw it.

By contrast, converting $100,000–$128,000 per year over the next 9 years converts roughly $900,000–$1.15M of the IRA at 22% or below. The remaining balance is smaller, RMDs are smaller, and the pension + RMD stacking is contained. The lifetime tax savings can reach $150,000–$300,000 depending on lifespan and investment returns.

State tax and the pension exemption asymmetry

Many states treat pension income more favorably than Roth conversion income — creating a potential tax asymmetry that affects the net benefit of converting.

Examples of the mismatch:

• States that exempt public pension income but tax Roth conversions: Several states exempt state and local government employee pensions from state income tax but treat Roth conversions as ordinary income. In these states, your pension occupies federal brackets at no state cost, while each conversion dollar adds to both federal and state tax liability.
• States with partial pension exclusions: Some states offer a partial exclusion for pension income (e.g., a fixed dollar amount) but cap it — so large pensions exceed the exclusion and create ordinary state income anyway. Conversions stack on top as regular income.
• No-income-tax states: If you live in a state with no income tax (Florida, Texas, Nevada, Washington, etc.), the pension vs. Roth conversion distinction is moot at the state level — only federal tax applies to both.

The practical question to ask: "Is my pension taxed by my state, and will my Roth conversion be taxed differently?" If the answer is that conversions are taxed while pension income is partially exempt, the after-tax cost of converting is higher than the federal-only calculation suggests. For a complete breakdown of how states tax Roth conversions, including states with no income tax and those with full retirement income exemptions, see our state taxes on Roth conversions guide.

Federal pensions: FERS and CSRS present two different profiles

Federal employees face pension-driven conversion math that varies significantly between the two retirement systems:

FERS (Federal Employees Retirement System): FERS annuities are typically more modest — often $30,000–$60,000 per year for a 25-30 year career. But FERS employees also receive Social Security and typically have significant TSP (Thrift Savings Plan) balances that, when rolled to a traditional IRA, create the same RMD pile-up problem. FERS retirees face both a pension reducing bracket room AND a future SS income that further compresses the window once claimed. The priority: convert aggressively in the years between FERS retirement and SS start (often ages 57-65), when the pension is the only income floor.

CSRS (Civil Service Retirement System, older federal employees): CSRS pensions are larger — often $60,000–$100,000 or more for a full career — and CSRS retirees receive no Social Security from their federal service (though some have SS from prior employment). The larger pension means more bracket compression, but the absence of SS income actually simplifies one variable. The SS torpedo interaction doesn't apply. With a $90,000 CSRS pension and no SS, the conversion room analysis looks exactly like the Patricia/Robert example above — no additional complexity from SS taxation phaseouts.

Federal employees should also note that TSP balances are subject to the same RMD rules as traditional IRAs once rolled over, and that in-service TSP-to-Roth-IRA rollovers are not permitted — the rollover must happen at or after separation from service.

When conversions are harder to justify for pension holders

Not every pension holder with a traditional IRA should convert. The case for conversions weakens when:

• The IRA balance is small relative to the pension. If your $60,000 pension is the dominant income source and your IRA is $150,000, conversions eliminate a small future RMD at meaningful tax cost today. The math is less compelling.
• The pension already pushes you into 22%+ and future RMDs aren't materially worse. If your pension puts you in the 22% bracket today and your RMDs will also land in the 22% bracket, the rate differential is zero and there's no gain from converting — you're simply paying the same rate earlier.
• No heirs or limited estate planning motivation. If you don't have children or heirs who would face inherited IRA distributions, the estate planning argument doesn't apply. The conversion must stand on its own lifetime tax math.
• Short conversion runway. If you're already 72 and RMDs begin imminently, there's limited time to convert at current rates before the RMD + pension + SS stack locks in your bracket anyway.