RMD Rules, Explained: Age 73, the Formula, and the Penalty
Educational explainer, not tax or financial advice — the worked figures below are computed at build time by the same tested engine that powers this site's RMD calculator, using the IRS Uniform Lifetime Table. Rules and ages reflect federal law as of September 2026 and change over time; irs.gov is the authoritative source.
A traditional 401(k) or IRA defers tax; it does not forgive it. Contributions generally go in pre-tax and every dollar withdrawn is taxed as ordinary income — which means the government has an interest in the money eventually coming out. The required minimum distribution (RMD) is the mechanism: starting at a set age, a minimum amount must leave most pre-tax retirement accounts each year, whether or not the owner needs the cash. The rules reduce to three pieces of arithmetic — a start age, a one-line formula, and a penalty percentage — and this guide walks through each, along with the accounts the regime exempts.
The start age: 73 now, 75 in 2033
Under the SECURE 2.0 Act, RMDs currently begin in the year the account owner turns 73, and the start age is scheduled to rise to 75 starting in 2033. The obligation attaches to pre-tax accounts — traditional IRAs and workplace plans such as traditional 401(k)s — because those are the accounts holding tax the IRS has not yet collected. The very first RMD has a special timing rule of its own, documented at irs.gov, and after that first year the deadline is annual.
Age 73 is the last stop on a longer schedule of retirement ages — 59½ for penalty-free access to most tax-advantaged accounts, 62 through 70 for the Social Security claiming window — and the sibling guide Retirement Age Milestones lays that full timeline out. This page stays on the RMD rules themselves.
The formula is one division
For a given year, the required minimum distribution is:
prior December 31 account balance ÷ the IRS life-expectancy factor for your age
For most account owners the factor comes from the Uniform Lifetime Table, published at irs.gov. The table assigns each age a divisor; the balance the account held on December 31 of the previous year, divided by that divisor, is the minimum that must come out. Here is the same $500,000 prior-year-end balance run through this site's tested engine at three ages, using the table divisors from the site's data file:
| Age reached this year | Uniform Lifetime Table divisor | RMD on a $500,000 balance | Share of the account |
|---|---|---|---|
| 73 | 26.5 | $18,867.92 | 3.77% |
| 80 | 20.2 | $24,752.48 | 4.95% |
| 90 | 12.2 | $40,983.61 | 8.2% |
The pattern is the point: the divisor shrinks each year, so the required percentage rises with age. That is by design — the schedule deliberately winds a tax-deferred account down over the owner's remaining life expectancy rather than letting deferral run forever. Note what the formula does not depend on: this year's market performance, income, or spending. Only last December 31's balance and this year's age enter the division.
The penalty arithmetic: 25%, reduced to 10%
Withdrawing less than the required amount triggers an excise tax on the shortfall — the gap between what was required and what actually came out. Under SECURE 2.0 that excise tax is 25% of the shortfall, reduced to 10% if the shortfall is corrected in a timely manner. The arithmetic on a $10,000 shortfall: $2,500.00 of excise tax, or $1,000.00 if corrected promptly — and the distribution itself, once taken from a pre-tax account, is still taxed as ordinary income on top. The excise tax is a penalty for lateness, not a substitute for the income tax.
The other direction is unrestricted: the RMD is a floor, not a ceiling, and withdrawing more than the minimum is always allowed. Whether a chosen withdrawal pace outlasts a portfolio is a different calculation entirely — the Retirement Withdrawal Calculator models that drawdown arithmetic, independent of what the IRS requires in any single year.
The Roth exemptions
The RMD regime exists to collect deferred tax, so accounts holding no deferred tax sit outside it. Roth contributions are made after tax and qualified Roth withdrawals are tax-free — there is nothing for a forced distribution to collect. Two exemptions follow. A Roth IRA has no lifetime RMDs for the original owner, full stop. And since 2024, Roth 401(k) accounts are exempt as well under SECURE 2.0 — before that change, workplace Roth accounts were subject to RMDs despite holding after-tax money. Inherited accounts, Roth included, follow separate distribution rules for beneficiaries; irs.gov covers those.
This asymmetry is one of the structural differences between the account types, alongside the basic tax mechanics: traditional accounts are generally funded pre-tax and taxed as ordinary income on the way out, Roth accounts are funded after tax with qualified withdrawals tax-free. The 401(k) Calculator and the Roth IRA Calculator model the accumulation side of each; contribution limits change annually and are published at irs.gov.
What the RMD calculator computes — and where it stops
The RMD Calculator performs exactly the division above: it takes a prior-year-end balance and the age reached this year, looks up the Uniform Lifetime Table divisor from a data file checked value-by-value against the IRS publication, and returns the required distribution with the divisor shown. That covers the common case — an account owner taking their own RMD.
Its boundary is just as explicit. It does not model inherited accounts, the separate IRS table that applies when the sole beneficiary is a much-younger spouse (irs.gov defines the exact threshold), or the aggregation rules for owners with multiple accounts — each of those changes the answer and belongs with the IRS worksheets or a professional. The divisors and the rules for keeping them current are documented on the methodology page.
Frequently asked questions
At what age do required minimum distributions start?
Under the SECURE 2.0 Act, RMDs currently begin the year the account owner turns 73, and the start age is scheduled to rise to 75 beginning in 2033. A special timing rule applies to the very first distribution; irs.gov documents it. Figures here reflect the law as of September 2026 and can change.
How is the RMD amount calculated?
One division: the account balance on December 31 of the prior year, divided by the IRS life-expectancy factor for the age reached this year. For most owners the factor comes from the Uniform Lifetime Table, published at irs.gov. At age 73 the table's factor is 26.5, so a $500,000 balance produces a $18,867.92 required distribution.
Do Roth accounts have RMDs?
A Roth IRA has no lifetime RMDs for the original owner, and since 2024 Roth 401(k) accounts are exempt as well (SECURE 2.0). The regime exists to collect deferred tax, and qualified Roth withdrawals carry none. Inherited accounts — Roth included — follow separate distribution rules described at irs.gov.
What is the penalty for missing an RMD?
An excise tax on the shortfall — the amount required but not withdrawn — of 25%, reduced to 10% if the shortfall is corrected in a timely manner under SECURE 2.0. That tax is on top of the ordinary income tax the distribution itself carries when it is eventually taken from a pre-tax account.
Is the RMD the most I can withdraw?
No — it is a floor, not a ceiling. Nothing prevents withdrawing more, and the RMD schedule is a tax rule, not a spending plan; whether a portfolio supports a chosen withdrawal rate over a full retirement is a separate arithmetic question from what the IRS requires in a given year.
Not tax or financial advice: an educational explainer of the account-owner RMD rules under the Uniform Lifetime Table — inherited accounts, much-younger spousal beneficiaries, and multiple-account aggregation differ. Statutory ages and percentages reflect the SECURE 2.0 Act as of September 2026 and change over time; confirm current figures at irs.gov or with a tax professional. Worked examples are computed at build time by the same tested engine as the calculators, so this page cannot drift from the tools. See the methodology page.