Retirement income planning isn’t just about having enough money — it’s about drawing it in the right order from the right accounts at the right time. The sequence of withdrawals across Social Security, required minimum distributions (RMDs), Roth accounts, pensions, and taxable investments can mean a difference of tens of thousands of dollars in lifetime taxes. It can also determine whether you trigger IRMAA Medicare surcharges, how much of your Social Security is taxed, and whether you have a tax-free inheritance to leave your heirs.

This guide lays out a framework for coordinating retirement income sources for tax-optimal outcomes.

The Four Buckets of Retirement Income

Most retirees have income coming from some combination of these sources:

  1. Social Security: Guaranteed inflation-indexed income; 0–85% may be taxable depending on your total income
  2. Traditional IRA / 401(k) / 403(b): Pre-tax accounts; every dollar withdrawn is ordinary income; subject to RMDs starting at age 73
  3. Roth IRA / Roth 401(k): After-tax accounts; qualified withdrawals are tax-free and not counted in income calculations; Roth IRAs have no RMDs during the owner’s lifetime
  4. Pension income: Usually fully taxable ordinary income; typically fixed and not flexible
  5. Taxable brokerage accounts: Capital gains rates apply; principal returns are tax-free; dividends may be qualified (lower rate) or ordinary

The goal is to draw income from each bucket in a way that minimizes total lifetime taxes while maintaining flexibility and preserving the most tax-advantaged assets for as long as possible.

The Foundation: Understanding How Retirement Income Is Taxed

Before building a strategy, you need to understand how these income streams interact with each other.

Social Security Taxation

Up to 85% of your Social Security benefit can be taxable, depending on your “combined income” (also called provisional income):

Combined income = Adjusted Gross Income + tax-exempt interest + 50% of Social Security benefits

Taxation thresholds (2025, single filers):

  • Combined income below $25,000: 0% of benefits taxable
  • $25,000–$34,000: up to 50% taxable
  • Above $34,000: up to 85% taxable

For married filing jointly: thresholds are $32,000 and $44,000.

This matters enormously: if you have $50,000 in RMDs, your Social Security triggers the 85% taxable tier, and you may pay ordinary income tax on a large portion of your benefits. See Social Security and taxes for a detailed walkthrough of the combined income calculation.

IRMAA: The Hidden Medicare Income Penalty

Income above certain thresholds also triggers higher Part B and Part D Medicare premiums through IRMAA (Income-Related Monthly Adjustment Amount). In 2025, IRMAA surcharges begin at $206,000 (married filing jointly) or $103,000 (single).

IRMAA uses income from two years prior: your 2025 Medicare premium is based on your 2023 tax return. A single year of high income — a large Roth conversion, an asset sale, an RMD spike — can trigger IRMAA surcharges that persist for that premium year.

See IRMAA Medicare surcharges for current brackets and planning strategies.

The RMD Problem

Required minimum distributions from traditional accounts start at age 73 and are calculated on the prior year-end balance divided by an IRS life expectancy factor. As your balance grows and the factor shrinks, RMDs increase — even if you don’t need the money.

For a retiree with a $2 million traditional IRA at 73, the first RMD is approximately $77,000 (using the 2025 Uniform Lifetime Table). By age 80, the RMD from the same balance could exceed $100,000 per year. Add a pension and Social Security, and total taxable income may push you into the 22–24% bracket while triggering IRMAA.

The solution is to reduce the traditional account balance before RMDs become large — through strategic Roth conversions.

The Core Strategy: The Pre-RMD Roth Conversion Window

The most powerful retirement income optimization available to most retirees is the pre-RMD Roth conversion window: the years between retirement (when earned income stops) and age 73 (when RMDs begin).

During this window, your taxable income often drops to its lowest retirement level: Social Security may be delayed, you’re no longer earning salary, and RMDs haven’t started. You can use this low-income period to convert traditional IRA funds to Roth at lower marginal rates.

How Roth conversion works:

  1. You withdraw money from your traditional IRA
  2. The withdrawal is ordinary income in the year of conversion
  3. You pay the tax now (ideally from non-IRA funds to avoid reducing the conversion amount)
  4. The converted funds grow tax-free and are never subject to RMDs

The optimal conversion amount: Convert up to the top of your current tax bracket, or up to just below an IRMAA threshold. For example:

  • If your income before conversions is $80,000 (MFJ) and the 22% bracket extends to $201,050, you could convert up to $121,050 at the 22% rate
  • But if converting $100,000 would push you above the first IRMAA threshold ($206,000 MFJ in 2025), you might stop at $125,000 to avoid a $2,000+ Medicare surcharge

This optimization requires year-by-year calculation. A tax professional or fee-only financial advisor is valuable here.

Roth Conversions and Social Security Timing

Roth conversions work best before you claim Social Security. Once Social Security begins, every dollar of additional income (including Roth conversion income) is computed in the combined income formula. Converting $50,000 from a traditional IRA while receiving $30,000 in Social Security benefits increases combined income by $50,000 (conversion) + $15,000 (50% of Social Security). This can push Social Security into the 85% taxable tier and accelerate your effective marginal rate.

See when to claim Social Security for a detailed analysis of how delayed claiming interacts with this planning.

Withdrawal Sequencing: Which Account First?

The conventional wisdom is to draw from taxable accounts first, then tax-deferred, then Roth last. This logic — preserve tax-advantaged growth as long as possible — is often correct, but not always optimal.

A better framework accounts for your actual tax situation:

Step 1: Cover Fixed Expenses with Fixed Income

Use income sources you can’t control first:

  • Pension payments (typically fixed)
  • Social Security (once you begin claiming)
  • Required minimum distributions (unavoidable at 73+)

Calculate what these sources cover. If they exceed your spending needs, you may have a pure tax management problem: how to deal with forced income you don’t need.

Step 2: Fill to the Top of Your Tax Bracket from Traditional Accounts

Once fixed income is determined, calculate how much room remains in your current tax bracket. Consider withdrawing (or converting to Roth) traditional IRA funds up to that limit. This “fills the bracket” while avoiding the higher rate of leaving all withdrawals to a higher-bracket future.

This approach is especially valuable for married couples where one spouse is significantly older — after the first death, the survivor files as single and faces lower bracket thresholds for the same income.

Step 3: Use Taxable Accounts for Flexibility

Taxable brokerage accounts have favorable tax treatment for long-term capital gains (0%, 15%, or 20% depending on income). Assets held in taxable accounts also receive a step-up in basis at death, effectively eliminating capital gains tax for inherited assets.

For retirees in the 0% capital gains bracket (taxable income below $94,050 for MFJ in 2025), taxable account withdrawals may be nearly tax-free. Harvesting gains in 0% bracket years is a powerful tax-reduction strategy.

Step 4: Save Roth for Last

Roth IRAs are the most flexible tax-advantaged account:

  • No RMDs during your lifetime
  • Tax-free growth
  • Tax-free withdrawals (qualified distributions)
  • Tax-free for inherited Roth IRAs (for the first 10 years)

Preserve Roth funds for:

  • High-income years when you need extra spending but want to avoid a higher tax rate
  • Large unexpected expenses (healthcare, home repairs)
  • Leaving to heirs (Roth IRA beneficiaries withdraw tax-free)

Roth 401(k) accounts must be rolled to a Roth IRA after retirement to avoid RMDs under the original owner.

Pension Income: The Fixed-Income Anchor

If you receive a defined benefit pension, it acts as an inflation-unadjusted (usually) fixed income stream that fills your lowest tax brackets first. A $40,000/year pension combined with $30,000 in Social Security already generates $70,000 in taxable income before any account withdrawals.

This compressed tax space means:

  • Less room for Roth conversions at low rates
  • Traditional IRA withdrawals will be taxed at higher rates
  • IRMAA thresholds may be easier to cross

Retirees with pensions and traditional IRA balances often face larger RMD problems because pension income already pushes them up the brackets. The pre-RMD conversion window is especially valuable for this group.

Pension timing decisions: Some pensions offer lump sum vs. annuity options. A lump sum in a high-income year can be expensive if it triggers a higher bracket. Rolling a lump sum to an IRA and doing Roth conversions over several years is often more tax-efficient than taking the lump sum as income.

Coordinating All Sources: A Worked Example

Consider a married couple, both 68:

  • Husband: $28,000/year Social Security (claiming delayed)
  • Wife: $20,000/year Social Security (claiming early)
  • Traditional IRA: $1.4 million combined
  • Roth IRA: $200,000
  • No pension
  • Annual spending need: $95,000

Their fixed income ($48,000 Social Security) covers roughly half their spending. They need $47,000 more.

Without planning: Take $47,000 from the traditional IRA each year until RMDs begin. At 73, RMDs start at approximately $54,000 and climb to $80,000+ by age 80. Combined income in later years triggers 85% Social Security taxation and potentially IRMAA.

With Roth conversion strategy (ages 68–72):

  • Their income is $48,000 (Social Security basis for tax purposes: $48,000 × 50% = $24,000 counted)
  • Traditional IRA withdrawal for spending: $47,000 (counts as income)
  • Total AGI before conversions: approximately $71,000
  • 22% bracket extends to $201,050 for MFJ in 2025
  • Convert an additional $80,000–$100,000 from traditional IRA to Roth each year while staying in the 22% bracket

Over five years (ages 68–72), this converts $400,000–$500,000 from traditional to Roth. This reduces the IRA balance from $1.4 million to roughly $900,000–$1 million at age 73, lowering the first RMD from approximately $54,000 to $35,000–$38,000. Combined income in later years is lower, keeping more Social Security out of the taxable tier and reducing IRMAA risk.

The cost: paying 22% tax on conversions now instead of potentially paying 22–24% (or more) later. The benefit: greater flexibility, lower lifetime tax, potential IRMAA savings, and a larger tax-free inheritance for heirs.

Key Tax-Planning Thresholds to Track Each Year

These are the brackets and thresholds that matter most for retirement income planning:

  • 0% capital gains bracket: MFJ up to $94,050 ordinary income (2025) — realize long-term gains at no federal tax
  • Roth conversion sweet spot: Fill to the top of 22% or 24% bracket without crossing IRMAA thresholds
  • Social Security 50% tier: Combined income above $32,000 (MFJ) — manage to stay below
  • Social Security 85% tier: Combined income above $44,000 (MFJ) — most retirees with pensions or large IRAs cross this
  • IRMAA Tier 1 threshold: $206,000 MFJ ($103,000 single) in 2025 income triggers surcharges two years later
  • Standard deduction (MFJ): $30,000 (2025) — income below this level may be effectively tax-free after deductions

Review these thresholds each December with your tax advisor or financial planner. Year-end Roth conversions can fill the bracket optimally before year-end.

Required Minimum Distributions: Managing the Mandatory Withdrawals

Once RMDs begin, they’re non-negotiable — but you have options for managing their tax impact:

Qualified Charitable Distributions (QCDs): If you’re 70½ or older and charitably inclined, you can direct up to $105,000 (2025) per year from your IRA directly to a qualified charity. A QCD counts toward your RMD but is not included in your adjusted gross income — effectively making it an above-the-line charitable deduction. For retirees in the 85% Social Security taxation tier, a QCD can reduce combined income dollar-for-dollar, reducing how much Social Security is taxed.

See required minimum distributions for QCD mechanics and other RMD management strategies.

Aggregate RMDs across multiple IRAs: You must calculate RMDs for each traditional IRA separately, but you can take the total from any combination of your traditional IRAs. This allows you to strategically draw down accounts with lower-performing investments or consolidate smaller IRAs.

Still-working exception: If you’re still working at 73+ and participate in your current employer’s 401(k), you may be able to delay RMDs from that account until you retire. This doesn’t apply to IRAs or to accounts at former employers.

Social Security Optimization Within This Framework

The decision of when to claim Social Security is one of the most impactful financial decisions in retirement. See when to claim Social Security for a full analysis.

From a pure income-coordination perspective:

  • Delaying Social Security from 62 to 70 increases the benefit by approximately 76% (8% per year from full retirement age to 70)
  • Delaying creates space for Roth conversions in early retirement before Social Security income triggers combined income calculations
  • The break-even age for delayed claiming is typically 80–83, but the tax benefits of delayed claiming plus Roth conversions often make delay advantageous well before the traditional break-even calculation

For couples, spousal Medicare strategies and Social Security spousal claiming interact with this framework. The lower-earning spouse often claims earlier; the higher-earner delays to maximize the survivor benefit.

Working with Professionals

A fee-only financial planner with expertise in retirement income distribution can model the specific numbers for your situation. The value of optimized withdrawal sequencing frequently exceeds the cost of professional advice — especially in the Roth conversion window years.

Key questions to bring to an advisor:

  • What is the projected RMD schedule from my current IRA balance?
  • How much can I convert to Roth each year while staying in the 22% or 24% bracket?
  • Does it make sense to delay Social Security given my health and the Roth conversion opportunity?
  • What is the IRMAA impact of my projected income in retirement?
  • Should my spouse and I have separate Roth conversion strategies given our age difference?

For more on the tax mechanics that underpin this strategy, see Social Security and taxes and required minimum distributions. For healthcare cost planning in retirement — which interacts significantly with income strategy — see healthcare costs in retirement and IRMAA Medicare surcharges.