Retirement Account Withdrawals Taxed by Account Type

The U.S. tax code does not treat all retirement account withdrawals alike. Whether a distribution is fully taxable, partially taxable, or tax-free at the federal level depends entirely on which account type produced it — and on when contributions to that account were taxed relative to the moment of withdrawal.

Three broad categories govern the mechanics: pre-tax accounts such as Traditional IRAs and 401(k) plans, where contributions were deducted and earnings grew tax-deferred; after-tax Roth accounts, where contributions were made with already-taxed dollars; and accounts containing a mixture of pre-tax and after-tax basis. Each category operates under a distinct set of IRS rules, and the interaction among them — especially when a retiree draws from multiple account types in the same year — determines total federal income tax liability on retirement distributions.

How the Tax Treatment of Each Account Type Actually Works

Traditional IRAs and pre-tax 401(k) plans. Contributions to a Traditional IRA that were deducted, and all pre-tax salary deferrals to a 401(k), were never subjected to federal income tax at the time they were made. Earnings inside those accounts also grew without current taxation. When distributions are taken, the entire amount — both the original contributions and the accumulated earnings — is included in the account holder's gross income for that year and taxed at ordinary income rates. The IRS treats these distributions as ordinary income, not as capital gains, regardless of how the underlying investments performed. Under IRC Section 72 and related guidance, every dollar coming out of a fully pre-tax account is a taxable dollar.

Roth IRAs and designated Roth 401(k) accounts. Roth contributions are made with after-tax dollars, meaning no deduction was taken at contribution. Provided the account satisfies the IRS's "qualified distribution" requirements — the account has been open for at least five tax years and the account holder is age 59½ or older, or another qualifying exception applies — distributions of both contributions and earnings are entirely excluded from federal gross income. The five-year rule and the age threshold are independent conditions; both must be met for earnings to come out tax-free. Contributions (not earnings) in a Roth IRA can always be withdrawn without tax or penalty at any time, because those dollars were already taxed. The mechanics of how Traditional and Roth IRA tax treatment differs at contribution and at withdrawal are governed by separate IRC provisions that apply regardless of investment performance inside the account.

Accounts with mixed basis (nondeductible Traditional IRA contributions). When a taxpayer made nondeductible contributions to a Traditional IRA — contributions for which no deduction was claimed — those dollars represent "basis" in the account. Distributions from such an account are partially taxable. The IRS requires a pro-rata calculation across all Traditional, SEP, and SIMPLE IRA balances the taxpayer holds: the ratio of total basis to total IRA value determines what fraction of any given distribution is excluded from income. This calculation is performed annually on Form 8606. A taxpayer cannot selectively withdraw only the basis portion; the pro-rata rule applies to the aggregate of all such accounts.

Required Minimum Distributions (RMDs). Once an account holder reaches the applicable RMD age — currently age 73 under the SECURE 2.0 Act for those who reached age 72 after December 31, 2022 — distributions from Traditional IRAs and most employer-sponsored plans become mandatory each year. These forced distributions are taxed under the same ordinary-income rules that apply to all pre-tax account withdrawals. Roth IRAs are not subject to RMDs during the original owner's lifetime, though designated Roth 401(k) accounts were subject to RMDs until the SECURE 2.0 Act eliminated that requirement for tax years beginning after 2023. The method by which required minimum distributions are actually calculated uses IRS life-expectancy tables applied to the prior year-end account balance.

Early distribution penalty. Distributions taken before age 59½ from most retirement accounts are subject to an additional 10 percent federal excise tax on top of ordinary income tax, unless a statutory exception applies. Exceptions include distributions due to death or disability, substantially equal periodic payments under IRC Section 72(t), and several others enumerated in the tax code. The penalty applies to the taxable portion of the distribution — meaning it applies fully to pre-tax accounts and to the earnings portion of a non-qualified Roth distribution, but not to Roth contribution basis.

Who Administers the Tax Mechanics at Each Stage

The plan administrator or IRA custodian — typically a brokerage or financial institution acting in a custodial role — is responsible for issuing Form 1099-R to the account holder and to the IRS each year a distribution is made. The 1099-R identifies the gross distribution, the taxable amount (when determinable), and a distribution code that signals the character of the payment to the IRS. For pre-tax accounts, the custodian typically reports the full distribution as taxable. For Roth accounts, the custodian reports the gross amount but codes the distribution so that the IRS can assess whether the qualified-distribution conditions have been met.

Federal income tax withholding from retirement distributions is subject to IRS rules. For distributions from IRAs, the default withholding rate is 10 percent, though the account holder may elect out. For periodic pension or annuity payments from employer plans, withholding is calculated using the withholding tables applicable to wages. The plan administrator or payer is responsible for executing this withholding and remitting it to the IRS.

The account holder — or the tax preparer acting on the account holder's behalf — bears responsibility for reporting the taxable amount on Form 1040 and, where basis is involved, for completing Form 8606 to track nondeductible IRA contributions and calculate the pro-rata exclusion. The IRS does not independently calculate the taxable portion of a mixed-basis distribution; that computation flows from the taxpayer's own records of prior nondeductible contributions.

For employer-sponsored plans such as 401(k) and 403(b) plans, the plan administrator also maintains records of any after-tax (non-Roth) contributions that may have been made, which affect the taxable fraction of distributions from those plans. The rules governing employer plan distributions are set by the IRC and enforced through IRS examination and DOL oversight of plan administration.

Where Account-Type Tax Rules Break Down or Produce Unexpected Results

The pro-rata rule catches taxpayers who hold multiple IRAs. A common misunderstanding arises when a taxpayer has both deductible and nondeductible IRA contributions across several accounts and attempts to convert or withdraw only from the account holding nondeductible dollars. The IRS aggregates all Traditional, SEP, and SIMPLE IRA balances for the pro-rata calculation. A taxpayer with $90,000 in a pre-tax rollover IRA and $10,000 in a nondeductible IRA cannot treat the $10,000 as fully after-tax for conversion purposes; only 10 percent of any distribution or conversion would be excluded from income, not 100 percent.

The five-year clock on Roth accounts resets for each new Roth IRA. Each new Roth IRA has its own five-year holding period that begins on January 1 of the tax year for which the first contribution was made to that specific account. This means a taxpayer who opens a second Roth IRA decades after the first cannot assume the original five-year clock carries over. Roth 401(k) accounts have a separate five-year clock from Roth IRAs, and the rules governing rollovers between them affect which clock governs the earnings.

Retirement income from pre-tax accounts can raise Medicare premiums. Large distributions from Traditional IRAs or 401(k) plans increase modified adjusted gross income (MAGI), which is the income measure used to determine whether the Income-Related Monthly Adjustment Amount (IRMAA) applies to Medicare Part B premiums. A distribution that pushes MAGI above a threshold bracket triggers a premium surcharge that takes effect two years after the income year in question. This interaction is not visible on the 1099-R itself and does not appear in retirement account statements.

State tax treatment does not mirror federal rules. Several states exempt some or all retirement income from state income tax, while others tax it fully. The account-type distinctions that govern federal taxation — pre-tax versus Roth, IRA versus pension — do not automatically map to state tax treatment. Each state administers its own exclusion rules, which may depend on the source of the income (public pension, private pension, IRA), the age of the recipient, or a fixed dollar exclusion. A distribution that is federally tax-free from a Roth account may still be reportable under a state's income tax rules if that state does not conform to the federal Roth exclusion.

The 1099-R taxable-amount box is sometimes left blank. For IRA distributions involving basis tracked on Form 8606, custodians often report the gross distribution but leave Box 2a (taxable amount) blank or mark Box 2b "taxable amount not determined." This is not an error; it reflects that the custodian does not have visibility into the taxpayer's cumulative basis records. The taxable amount must then be calculated by the taxpayer using Form 8606, and the IRS expects that computation to match the 1099-R gross figure minus the allowable exclusion.

What a Retirement Account Statement and Tax Form Show — and What They Do Not

An annual account statement from a plan administrator or IRA custodian shows the account balance, contributions made during the year, distributions taken, and investment activity. It does not show the tax character of those distributions. A statement showing a $30,000 withdrawal does not indicate whether that withdrawal was fully taxable, partially taxable, or tax-free — that determination requires reference to the account type and the taxpayer's contribution history.

Form 1099-R, issued by January 31 following the distribution year, is the primary tax document for retirement distributions. Box 1 shows the gross distribution. Box 2a shows the taxable amount, when the payer can determine it. Box 7 contains a distribution code — for example, code 7 for a normal distribution from a qualified plan after age 59½, or code Q for a qualified Roth distribution. The distribution code is what signals to the IRS how the payment should be treated. A code of Q on a Roth distribution, for instance, indicates the distribution meets the qualified-distribution standard and is excludable from income.

Form 8606 is the IRS form on which taxpayers track nondeductible IRA contributions and calculate the nontaxable portion of distributions from accounts containing basis. It is filed with the annual tax return and carries forward the cumulative basis from year to year. Without a complete Form 8606 history, a taxpayer cannot accurately compute the taxable fraction of distributions from a mixed-basis IRA. The IRS does not independently maintain this basis record; it exists only in the taxpayer's own filing history.

Neither the 1099-R nor the account statement reflects the state tax treatment of a distribution. State taxability is determined separately under each state's own tax return instructions and is not indicated on any federally issued document.

The federal tax system's account-type distinctions — pre-tax, Roth, and mixed-basis — were built into the retirement savings code over several decades through separate legislative acts, and the rules governing each type reflect the timing of when taxes were collected relative to when the money was saved. The result is a layered structure in which the same dollar amount withdrawn in the same year can carry entirely different tax consequences depending solely on which account it came from.

Note: This explains how a retirement system works. It is not financial, tax, or legal advice, it is not specific to any individual's retirement, and it is not a substitute for a licensed financial, tax, or legal professional. Rules, ages, and dollar limits change by year — check the cited sources.