RMD Calculator Explained

The withdrawal the IRS makes you take whether you want to or not

For most of your working life, a Traditional IRA, 401(k), or 403(b) is a one-way valve — money goes in pre-tax, and the IRS waits. The wait ends at the year you turn 73 (or 75 if you were born in 1960 or later), when you must start withdrawing a minimum amount every year. That number is the Required Minimum Distribution, and the RMD calculator tells you what it is from two inputs: your prior-year-end account balance and the age you reach this calendar year. The math is a single division — balance over the IRS Uniform Lifetime Table divisor — but the rules around it (which accounts count, which ages apply, what happens if you miss) are where most retirees get tripped up.

Every figure in this article comes from IRS Publication 590-B and the post-SECURE 2.0 framework set out in the SECURE 2.0 Act of 2022. The Uniform Lifetime Table the RMD calculator uses is the version updated effective 2022 under Treasury final regulations TD 9930, which produced slightly smaller annual RMDs than the older table by adding roughly a year and a half of life expectancy across all ages.

What an RMD actually is

A Required Minimum Distribution is the smallest amount the IRS lets you withdraw from a tax-deferred retirement account in a given year, once you are past the start age. The point of the rule is fiscal, not protective — Congress gave you a tax deduction decades ago when you put the money in, and now wants the tax revenue back. Without RMDs the most affluent retirees could leave the money invested forever and pass it to heirs untaxed; RMDs force a steady drawdown.

The RMD is a floor, not a ceiling. You can always withdraw more than the minimum — there is no upper cap on tax-deferred withdrawals — but you cannot withdraw less. The amount itself is treated as ordinary income on your federal return in the year you take it, plus state income tax where applicable. Custodians default to withholding 10% for federal tax, and you can adjust that on the distribution form.

The maths the calculator runs

The formula is one line:

RMD = prior-year-end balance ÷ distribution period

"Prior-year-end balance" is the fair market value of the account on December 31 of the previous year, as reported by your custodian on Form 5498 in May. "Distribution period" is a number of years the IRS looks up in the Uniform Lifetime Table, indexed by the age you reach in the current calendar year. The table runs from age 72 (divisor 27.4) to age 120 (divisor 2.0); ages above 120 stay at 2.0. The divisor shrinks each year, so the implied withdrawal rate climbs from about 3.65% at age 73 to 50% at age 120. The RMD calculator does the lookup, the division, and shows the corresponding monthly equivalent and post-withdrawal balance.

A note on the table itself: the divisor at each age is the joint life expectancy of you and a hypothetical beneficiary exactly 10 years younger. That assumption is baked into the Uniform Lifetime Table, and it is why almost everyone uses it regardless of whether they have a named beneficiary at all. The exception — covered later — is the small group whose sole beneficiary is a spouse more than 10 years younger.

Worked example: $250,000 at age 75

A 75-year-old retiree had $250,000 in a traditional IRA on December 31 of last year. They look up age 75 in the Uniform Lifetime Table and find a divisor of 24.6 years. The RMD for this year is:

$250,000 ÷ 24.6 = $10,162.60

That is the floor. They could take it as one lump sum in December, in twelve monthly instalments of $846.88, in two semi-annual payments, or on any schedule they like — the IRS only requires the total to clear the account by December 31. The withdrawal rate is 1 / 24.6 = 4.07%, meaning their first RMD eats just over 4% of the balance. Run the same inputs through the RMD calculator and the page shows the same $10,162.60 plus the monthly equivalent and the $239,837.40 remaining balance.

A year later, assume the account grew to $260,000 by year-end. At age 76 the divisor is 23.7, and the RMD becomes $260,000 ÷ 23.7 = $10,970.46 — about 4.22% of the new balance. The numerator (balance) moves with markets and contributions; the denominator (divisor) drops about one year at a time. The implied withdrawal rate is almost entirely controlled by your age.

Which accounts have RMDs

Most tax-deferred US retirement accounts trigger RMDs. The list:

Traditional IRA, SEP-IRA, SIMPLE IRA

All three follow the Uniform Lifetime Table. Where you hold multiple IRAs at different custodians, you compute the RMD on each one separately, then aggregate the total and withdraw it from any single IRA or any combination. The IRS only checks that the total cleared.

401(k), 403(b), 457(b), and the federal Thrift Savings Plan

Workplace-style defined-contribution plans all require RMDs. Unlike IRAs, they cannot be aggregated across plans — if you have an old 401(k) at Employer A and a current 401(k) at Employer B, each needs its own RMD withdrawal from that specific plan. The same is true for 457(b) and the TSP. The one cross-aggregation rule that does work is across multiple 403(b)s: aggregate the RMD across all 403(b)s and withdraw from any one.

Inherited IRAs and 401(k)s

Beneficiary accounts follow their own rules, primarily the 10-year rule introduced by the SECURE Act of 2019: non-spouse beneficiaries who inherited a retirement account from someone who died after 2019-12-31 must empty the account within 10 years. Annual RMDs during that window depend on whether the original owner was already taking RMDs at death. Spousal heirs, minor children, disabled or chronically ill heirs, and heirs less than 10 years younger than the decedent have separate treatment. This calculator does not handle inherited accounts — the RMD calculator is built for the original owner's lifetime RMD only.

Roth IRAs and (now) Roth 401(k)s

Roth IRAs never require RMDs during the owner's lifetime. Under SECURE 2.0, effective 2024, Roth 401(k) and Roth 403(b) accounts also no longer require RMDs while the owner is alive — a change from the prior rule that forced Roth-401(k) holders to roll their balance to a Roth IRA to escape RMDs. Designated Roth balances in workplace plans are now treated like Roth IRAs for RMD purposes.

When RMDs start: 73, 75, and the SECURE 2.0 reshuffle

The original SECURE Act (December 2019) lifted the start age from 70½ to 72. SECURE 2.0 (December 2022) lifted it again, in two stages:

• Born before 1951 — start age was 70½ or 72, already in effect
• Born 1951 to 1959 — start age is 73 (first RMD in the year you turn 73)
• Born 1960 or later — start age is 75 (first RMD in the year you turn 75)

The first RMD has a one-time deferral option: you can take it any time up to April 1 of the year after you reach the start age — the "required beginning date." Every subsequent RMD must be taken by December 31 of its own year. Delaying the first RMD until the following April means taking two RMDs in the same calendar year, which usually pushes total income into a higher bracket and increases the Medicare IRMAA surcharge two years later. Most retirees take the first RMD on the normal December schedule.

What happens if you miss an RMD

Missing the deadline used to be brutal: a 50% excise tax on the shortfall under IRC §4974. SECURE 2.0 cut that to 25%, and to 10% if you correct the shortfall within a two-year "correction window" that ends on the earlier of (a) the date the IRS sends a deficiency notice or (b) the second 31 December after the missed year. To correct: withdraw the missed amount, file Form 5329, and request a waiver of the excise tax under the reasonable-error exception with an explanation attached. The IRS has historically been lenient on first-time waivers when the shortfall was small and the cure was prompt.

Strategies retirees use around RMDs

Qualified Charitable Distribution (QCD)

If you are at least 70½ and charitably inclined, a QCD sends up to $108,000 in 2025 directly from your IRA to a qualified public charity. The amount counts toward your RMD but is excluded from your taxable income — better than itemising the charitable deduction, because it lowers your adjusted gross income (AGI), which cascades into Medicare IRMAA, Social Security taxability, and ACA premium subsidies. QCDs must come from a Traditional, Inherited, or rollover IRA, not from a 401(k). The annual cap is indexed for inflation and Treasury sets the 2026 number in late 2025.

Roth conversions before the RMD years

The years between retiring (often early 60s) and reaching the RMD start age (73 or 75) are sometimes called the "tax-bracket valley" — earned income has stopped but Social Security and RMDs have not yet started, leaving a wide window of low-marginal-rate tax years. Retirees in that window often convert chunks of Traditional IRA to Roth, paying tax at low rates today to shrink the future RMD base. How much to convert depends on your bracket, expected return on the money, and heirs' tax rates. A back-of-envelope model lives in the IRA calculator on the Traditional-vs-Roth comparison.

Take RMDs in kind, not cash

The "withdrawal" can be an in-kind transfer of securities to a taxable account instead of a cash sale. Same tax bill on the value of the securities transferred, but you keep the position rather than selling into a down market. Useful in years when the account is mostly long-duration assets you would otherwise be forced to liquidate at a bad price.

The 401(k) "still working" exception

If you are still employed by the plan sponsor at the RMD start age, and you are not a 5%-or-greater owner of the company, you can delay the RMD from that specific 401(k) until you actually retire. The exception does not extend to IRAs or to old 401(k)s with prior employers, which still need their RMDs on the normal schedule.

The younger-spouse table

Where your sole beneficiary is a spouse more than 10 years younger than you, the IRS lets you use the Joint Life and Last Survivor Expectancy Table (Pub 590-B, Table II) instead of the Uniform Lifetime Table. The Joint Life table gives a larger divisor and therefore a smaller RMD. This calculator does not implement that case — it requires both ages and only applies to a narrow slice of owners. Your IRA custodian usually handles the calculation automatically if you have flagged the beneficiary correctly.

Common mistakes

Aggregating 401(k) RMDs across plans

IRA RMDs aggregate; 401(k) RMDs do not. Taking the full year's RMD from one of two 401(k)s leaves the other 401(k) short, and the IRS treats it as a missed RMD on that specific plan. If you are about to retire from a workplace plan, consider rolling the old 401(k) into an IRA first — once it is in an IRA, it joins the aggregation pool.

Forgetting the prior-year-end balance is fixed

The RMD for 2026 is based on the December 31 2025 balance, not the balance today. Markets move, but the divisor is anchored to a snapshot. A big drawdown in early 2026 does not reduce the 2026 RMD. The custodian's January statement is the source of truth.

Treating RMDs as a withdrawal cap

RMDs are the floor, not the ceiling. Some retirees believe they cannot withdraw more than the RMD without penalty. Not true — there is no upper limit, only ordinary-income tax on whatever you take. If you need more, take more.

Double counting QCDs

A QCD can count toward the RMD and reduce AGI, but you cannot also claim a charitable deduction on the same dollars. The custodian reports a QCD on Form 1099-R the same as any other distribution; you flag it as a QCD on your tax return. Get this wrong and the IRS gets the dollars twice.

When to talk to a tax professional

The mechanics in this article cover the standard case — original IRA or 401(k) owner, single account, Uniform Lifetime Table, no inherited money. Three situations push you out of the standard case and into territory where a CPA or fee-only fiduciary planner earns their fee: inherited accounts (10-year rule, RMD-during-the-window question, sub-trust rules), Roth conversion ladders sized to stay below specific bracket or IRMAA thresholds, and any year where you are also taking Social Security and Medicare premiums for the first time. Tax software handles the arithmetic; humans handle the strategy.

Frequently asked questions

At what age do RMDs start?

The start age depends on your year of birth. People born between 1951 and 1959 start at age 73; people born 1960 or later start at age 75. Those born before 1951 are already past the start age (which was 70½ or 72 under earlier rules). The "start year" is the calendar year you reach the start age — not the day of your birthday.

Which IRS table does this calculator use?

The RMD calculator uses the Uniform Lifetime Table (IRS Publication 590-B, Appendix B, Table III) as updated effective 2022. That is the correct table for the vast majority of account owners — the only exception is a sole beneficiary spouse more than 10 years younger, who triggers the Joint Life and Last Survivor Expectancy Table.

What if I miss the deadline?

The excise tax is 25% of the shortfall, reduced to 10% if you correct within two years. To correct, withdraw the missed amount, file Form 5329, and request a waiver under the reasonable-error exception. The IRS often grants the waiver for first-time, small-dollar misses.

Are RMDs taxed?

Yes — ordinary income at your federal marginal rate, plus state income tax where applicable. Default federal withholding is 10%, adjustable on the distribution form. RMDs from Roth IRAs do not exist during the owner's lifetime, and effective 2024 the same is true for Roth 401(k)s.

Can I reinvest the RMD?

You cannot roll the RMD back into another IRA or 401(k) — that is a prohibited rollover. You can put the cash into any taxable account (brokerage, savings, money-market) once you have paid the tax on the distribution. The funds keep growing; they just lose their tax-deferred wrapper.

Do RMDs apply to Roth IRAs?

No. Roth IRAs never required RMDs during the owner's lifetime, and effective 2024 Roth 401(k) and Roth 403(b) accounts also no longer require lifetime RMDs under SECURE 2.0. Roth balances passed to beneficiaries do generally fall under the 10-year rule, but that is an inherited-account rule, not an owner-account rule.

Does the calculator handle multiple accounts?

The RMD calculator computes one RMD at a time. For multiple IRAs, run the calculator on each balance, sum the results, and take that total from any one IRA or combination. For multiple 401(k)s, run the calculator on each balance and take each RMD from its specific plan — 401(k) RMDs do not aggregate.

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