Retirement tax planning requires decisions today based on tax rates, investment returns and personal circumstances that may not become clear for decades. The wrong Roth conversion can create an unnecessary tax bill, while waiting too long can leave retirees trapped by required withdrawals and higher lifetime taxes.
The Problem Hiding Inside Traditional Retirement Accounts
Traditional IRAs and 401(k)s offer an attractive bargain during a worker’s highest-earning years: contribute pretax dollars today and defer the tax until retirement.
For disciplined savers, that bargain can eventually become complicated.
Decades of contributions and investment gains can produce an account large enough to generate substantial required minimum distributions, or RMDs. Those withdrawals are generally taxed as ordinary income, whether the retiree needs the money or not.
RMDs currently begin at age 73 for people born from 1951 through 1959. The starting age rises to 75 for those born in 1960 or later.
A large required withdrawal can do far more than increase an investor’s federal income-tax bill. Additional income may cause more Social Security benefits to become taxable, raise Medicare premiums, reduce the value of certain deductions and make other investment income more expensive.
That creates a frustrating reality: A retirement account can be highly successful from an investment perspective while becoming increasingly inefficient from a tax perspective.
The central challenge is timing. Savers must decide whether to pay taxes now through Roth contributions or conversions, or defer those taxes and accept whatever rates and rules exist later.
Congress makes that decision harder. Total U.S. public debt crossed $40 trillion in 2026, intensifying the long-term possibility of higher tax rates, narrower deductions or entirely new sources of federal revenue. None of those outcomes is guaranteed, but ignoring the risk is its own tax bet.
Your Tax Bracket Is Only the First Number That Matters
Most Roth conversion decisions begin with a comparison between two rates:
- The tax rate paid on the conversion today.
- The expected tax rate on the money when it is eventually withdrawn.
If an investor can convert money at 12% today and reasonably expects to pay 22% later, the conversion may be attractive. Paying 32% today to avoid a likely 22% rate later is much harder to justify.
That simple comparison is useful, but incomplete.
A large conversion increases adjusted gross income in the year it occurs. That increase can trigger several secondary costs:
- Higher Medicare Part B and Part D premiums through income-related monthly adjustment amounts.
- More taxable Social Security benefits.
- Higher taxes on dividends and capital gains.
- Exposure to the 3.8% net investment income tax.
- Reduced eligibility for income-based deductions, credits or subsidies.
- Higher state income taxes.
Investors should therefore focus on the effective marginal cost of a conversion, rather than looking only at the published federal tax bracket.
A retiree technically in the 22% bracket might face a meaningfully higher effective rate once Medicare surcharges and taxes on additional Social Security income are included. A conversion that appears sensible on the surface can become expensive after those interactions are counted.
The Retirement Tax Window Most Savers Miss
For many investors, the best opportunity for Roth conversions appears during the years immediately after retirement.
Earned income may decline sharply once a person stops working. At the same time, Social Security may not have started and RMDs may still be years away. That can create a temporary period of unusually low taxable income.
This is the retirement tax window.
Suppose a couple retires at 64 with substantial traditional IRA balances. They delay Social Security and do not face RMDs until age 73 or 75. During the intervening years, they may have room to convert portions of their traditional IRAs while remaining inside relatively moderate tax brackets.
Once Social Security and RMDs begin, that opportunity can narrow or disappear.
The goal should rarely be to convert an entire traditional IRA as quickly as possible. A more controlled approach is to convert enough each year to use a targeted tax bracket without unnecessarily crossing into a significantly more expensive one.
This allows investors to spread the tax bill across multiple years while gradually reducing future RMDs.
Why a Market Crash Changes the Calculation
Roth conversions carry an investment risk that receives too little attention.
Taxes on a conversion are based on the account’s value when the conversion occurs. If an investor converts $200,000 and the converted assets subsequently fall to $140,000, the original tax bill does not fall with the portfolio.
Current law generally does not allow a completed Roth conversion to be reversed through recharacterization.
That makes conversion timing important. Investors who convert a very large amount after an extended market rally may be exposing themselves to both a high tax bill and near-term market risk.
One practical response is to divide a planned annual conversion into several smaller transactions. This cannot eliminate market risk, but it reduces the chance that the entire conversion occurs near a temporary market high.
A downturn can also create an opportunity. Converting depressed assets allows investors to move more shares into a Roth account for the same taxable dollar amount. If the assets recover, the subsequent growth can occur inside the Roth.
Traditional accounts offer a different form of downside protection. When account values decline, future taxable withdrawals and RMDs may decline as well. In effect, the government shares in a portion of the loss through lower future tax revenue.
That is one reason a full conversion is not automatically the safest choice.
Already Taking RMDs? Conversions Are Still Possible
Retirees who have started RMDs can continue converting traditional IRA funds to Roth accounts.
The required distribution itself cannot be converted. The full RMD must generally be withdrawn first, and any conversion occurs afterward.
This can make conversions more expensive because the RMD has already consumed part of the retiree’s lower tax brackets. A conversion added on top of that income may face a higher marginal rate or trigger additional Medicare costs.
Even so, partial conversions may remain useful when they reduce future RMDs, protect a surviving spouse from higher single-filer tax rates or improve the tax treatment of an inheritance.
The analysis should consider lifetime family taxes, rather than focusing exclusively on the account owner’s current-year bill.
The Charitable Strategy That Can Beat a Roth Conversion
Charitably inclined IRA owners have another powerful option.
Beginning at age 70½, eligible IRA owners can make qualified charitable distributions, or QCDs, directly from an IRA to qualifying charities. The annual QCD limit is $111,000 in 2026.
A QCD can satisfy all or part of an RMD without adding the distributed amount to adjusted gross income.
That distinction is valuable. A regular IRA withdrawal followed by a charitable donation increases gross income first and depends on the taxpayer receiving an offsetting deduction. A QCD keeps the eligible distribution out of adjusted gross income entirely.
This can help limit Medicare surcharges, the taxation of Social Security benefits and other income-based costs.
For an investor who expects to donate traditional IRA assets to charity, paying tax to convert those dollars to a Roth may be counterproductive. A charity can generally receive traditional IRA money without owing income tax, either through QCDs during the owner’s lifetime or as a designated beneficiary.
Charitable intent can therefore justify keeping part of a traditional IRA intact.
Long-Term Care Creates a Surprising Reason to Preserve Taxable IRA Money
Retirees without long-term care insurance should also be cautious about converting every available traditional IRA dollar.
Qualified long-term care expenses can count as deductible medical expenses when the taxpayer itemizes deductions, subject to applicable rules and the threshold of 7.5% of adjusted gross income. Because nursing care and other qualified services can be extremely expensive, some retirees may accumulate substantial medical deductions.
Traditional IRA withdrawals used to pay those expenses create taxable income that may be partially offset by the medical deductions.
Roth withdrawals do not create taxable income. That is normally an advantage, but it also means large medical deductions could go unused if the retiree has little taxable income available to offset.
Keeping a reserve in traditional accounts may provide tax-efficient funding for future care. The appropriate amount depends on insurance coverage, health, other income sources and the likelihood of itemizing medical expenses.
Tax Diversification May Be More Valuable Than Tax Minimization
The obvious objective is to pay the lowest possible tax rate. The stronger objective is to preserve flexibility across several possible futures.
Taxable brokerage accounts provide accessible assets and preferential rates on qualified dividends and long-term capital gains, although they can generate annual taxable income.
Traditional retirement accounts provide an upfront deduction and defer taxes, but eventually produce ordinary income and RMDs.
Roth accounts require after-tax contributions or taxable conversions, while offering tax-free qualified withdrawals and no lifetime RMDs for the original owner.
Holding money across all three account types allows retirees to choose where their spending money comes from each year.
During a high-income year, a retiree may draw from Roth funds. During a low-income year, traditional withdrawals or conversions may fill unused tax brackets. Taxable assets can provide additional flexibility and may receive favorable treatment when passed to heirs under current law.
This flexibility has an option value. It reduces dependence on any single prediction about Congress, investment returns, longevity or future spending.
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