How do you plan retirement taxes across multiple years?

TL;DR. Model every year from retirement through age 100: project income sources, federal tax brackets, required minimum distributions, Social Security taxation, and Medicare IRMAA surcharges — then identify the years with bracket headroom for Roth conversions and accelerated withdrawals. A multi-year retirement tax planning calculator automates this projection so advisors and retirees can sequence withdrawals across accounts for the lowest lifetime tax bill.

Why single-year tax planning is not enough

Retirement tax planning is a sequencing problem, not a single-year math problem. A retiree who minimizes taxes this year often pays more over a 30-year retirement because they miss the low-bracket windows between retirement and the start of RMDs or Social Security. The goal of multi-year tax bracket management is to smooth taxable income across decades so no single year spikes into an expensive bracket or triggers IRMAA.

Here is a worked example. Assume a married-filing-jointly couple retires at 63 with $2.1M in a traditional IRA and $180,000 in a Roth. They have no pension and will claim Social Security at 67. Between ages 63 and 66, their only taxable income is a small brokerage dividend of $28,000. After the $30,050 standard deduction for MFJ, taxable income is roughly zero — they are sitting in the 10% bracket with over $23,850 of room they are wasting every year.

A multi-year projection reveals the opportunity: convert $70,000 to $80,000 from the traditional IRA to the Roth each year for four years. Each conversion fills the 10% and 12% brackets (up to $96,950 MFJ), costing about $8,500 to $9,700 in federal tax per year. By age 67, they have shifted $280,000 to $320,000 into the Roth at an average effective rate under 13%. When Social Security and RMDs begin, their traditional IRA balance is lower, producing smaller RMDs, lower provisional income for Social Security taxation, and less risk of crossing an IRMAA threshold. The lifetime tax savings compared to a no-conversion baseline routinely exceeds $60,000 to $100,000 in this scenario.

Try it with your numbers

What a good multi-year retirement tax calculator should show

• Year-by-year bracket map — projected taxable income, marginal rate, and effective rate for each year from current age through age 100
• Roth conversion optimizer — identifies the dollar amount of conversion that fills a target bracket in each low-income year without crossing into the next tier
• RMD projection — calculates required minimum distributions under SECURE 2.0 (age 73 or 75 start) and shows how pre-RMD conversions reduce future RMD amounts
• IRMAA lookback modeling — flags every year where MAGI would cross an IRMAA tier and shows the two-year-lagged Medicare premium surcharge impact
• Social Security provisional income — calculates the percentage of benefits taxable (0%, 50%, or 85%) in each year and shows how withdrawal sequencing changes that percentage

AdvisorCal's Retirement Tax Calculator handles all of the above in a single view. If you also want to model Roth conversion tax in isolation, RMD calculations, IRMAA threshold details, or bracket-by-bracket analysis, those tools are included in the same subscription.

Key facts

• 2026 federal brackets (MFJ): 10% up to $23,850 | 12% to $96,950 | 22% to $206,700 | 24% to $394,600 | 32% to $501,050 | 35% to $751,600 | 37% above.
• RMD start age (SECURE 2.0): Age 73 for those born 1951-1959; age 75 for those born 1960 or later. Missing an RMD incurs a 25% excise tax (reduced from 50%), or 10% if corrected within two years.
• Social Security taxation thresholds (MFJ): Provisional income above $32,000 makes up to 50% of benefits taxable; above $44,000 makes up to 85% taxable. These thresholds are not inflation-adjusted and have not changed since 1993.
• IRMAA Tier 1 (2026 MFJ): MAGI above $212,000 triggers higher Medicare Part B and Part D premiums two years later. Each subsequent tier adds roughly $1,000-$4,000/year in per-person surcharges.
• Standard deduction (2026 MFJ): $30,050 ($31,850 if both spouses are 65+). The extra deduction for age 65+ creates additional bracket room that multi-year planning should capture.
• Bracket inflation indexing: Federal brackets adjust annually for CPI. A multi-year projection should inflate bracket thresholds at 2-3% per year to avoid overstating future tax liability.

Common follow-ups

What is the best withdrawal order for retirement accounts? The conventional wisdom — spend taxable accounts first, then tax-deferred, then Roth last — is a starting point, not a rule. Multi-year tax planning often reveals that blending withdrawals from all three account types in specific ratios each year produces a lower lifetime tax bill than any strict ordering. The optimal sequence depends on projected Social Security, pension income, RMD timing, and state tax rules. A retirement tax strategy calculator models these variables simultaneously rather than applying a one-size-fits-all rule.

How do Roth conversions fit into a multi-year tax plan? Roth conversions are the primary lever in multi-year tax bracket management. The strategy is to identify years where taxable income is naturally low — typically between retirement and the start of Social Security or RMDs — and convert enough traditional IRA dollars to fill the current bracket without crossing into the next one. Each conversion reduces future RMDs, lowers future Social Security provisional income, and shifts growth into the tax-free Roth. See the Roth conversion tax calculation page for bracket-level detail.

How does IRMAA affect multi-year retirement tax planning? Medicare IRMAA uses modified adjusted gross income from two years prior to set Part B and Part D premiums. A Roth conversion or large capital gain in 2026 affects premiums in 2028. Multi-year planning must track MAGI against every IRMAA tier — not just the first one — because each tier jump adds $1,000 to $4,000+ per person per year in extra premiums. The IRMAA threshold breakdown details every tier for 2026.

Should I factor in state taxes when doing multi-year planning? Yes. Nine states have no income tax, but the other 41 (plus DC) impose their own brackets, and some differ significantly from federal. A client who retires in California and later moves to Florida may benefit from accelerating conversions before the move. State tax is a meaningful variable in any multi-year retirement tax strategy calculator.

When this doesn't apply

Multi-year tax projection adds the most value for clients with significant pre-tax retirement balances ($500K+) and a gap between retirement and the start of Social Security or RMDs. Clients whose retirement income is almost entirely from Roth accounts, pensions taxed at source, or Social Security below the provisional income threshold gain little from multi-year bracket management. Clients with highly variable income (e.g., rental properties, business sale proceeds) may find projections unreliable beyond a few years and should rerun annually. This tool models federal taxes — state-specific calculations require state-level inputs not included in the base projection.

Sources

• IRS — Tax Rate Schedules
• IRS — Retirement Topics: Required Minimum Distributions
• IRS — Social Security Benefits Taxation
• CMS — Medicare Part B Premiums and IRMAA

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