The Default Sequence Is Wrong
The textbook withdrawal order is taxable first, then pre-tax, and finally Roth. It sounds logical: defer taxes as long as possible, maximize tax-sheltered compounding, and drain the cheapest bucket first. Say this at any retail financial planning seminar and the entire room will nod in agreement. It is also a recipe for an avoidable seven-figure tax bill.
If your pre-tax Traditional IRA or 401(k) balance is large enough that future Required Minimum Distributions will push you into the 24% or higher bracket—which in 2026 dollars means a pre-tax balance of roughly $1.5M for singles or $2M for married couples filing jointly—this default strategy fails spectacularly. While you live off taxable cash in your 60s, your pre-tax accounts compound unchecked. At age 73 or 75, the RMD mandate kicks in. The IRS forces massive distributions based on your prior year-end balance, stacking these taxable distributions on top of your Social Security benefits. The resulting marginal tax rate on every subsequent dollar of ordinary income, capital gains, and Roth conversions will be permanently higher for the rest of your life.
The smart sequence is blended. In each year of retirement you ask: what is the cheapest bracket still open, and how do I fill it without crossing the next cliff? Cash for living expenses comes from the bucket whose marginal cost this year is lowest; everything else gets converted or realized to fill cheap space. In practice:
- Early retirement (pre-Social-Security, pre-RMD): draw from pre-tax accounts and execute Roth conversions aggressively up to the IRMAA-or-NIIT ceiling you have targeted. Use taxable cash for living expenses to keep your reported income from overshooting the limit.
- Bridge years (between Social Security claim and RMDs): a narrower window with smaller conversions, but still highly productive.
- RMD years: convert only the remaining headroom between your forced RMD and your targeted tier ceiling. Spend RMDs first, taxable next to satisfy cash needs without growing AGI, and let Roth balances compound untouched.
- Late life (80s+): pre-tax balances are mostly depleted or under control; living expenses are funded by Roth and taxable withdrawals; bequest optimization (section “What to Spend, What to Leave”) takes precedence.
This is not a minor tweak. For a household entering retirement at age 62 with $4M pre-tax and $1M taxable, a blended-fill strategy can leave on the order of $1M to $2M more after-tax wealth to the family by age 90 than the default sequence under typical return assumptions, driven almost entirely by systematic Roth conversions in cheap brackets.