RMDs explained: the forced-withdrawal clock

Every dollar in a traditional retirement account went in untaxed, and that arrangement was never permanent. A required minimum distribution is the collection notice. Starting at an age set by statute, the owner of a pretax account has to move a defined fraction of it out each year and report the amount as ordinary income. Nothing obliges you to spend the money — it can land in a taxable brokerage account the same afternoon, still invested — but the tax is owed whether you needed the withdrawal or not.

That distinction, taxed versus spent, is most of the subject. An RMD is not a spending plan and it is not a safe withdrawal rate; it is a schedule for recognizing income the government has been waiting decades on. The expensive mistakes cluster at two extremes: treating the minimum as a retirement income plan because it happens to be a number someone else calculated, or ignoring the schedule entirely until it arrives on top of a pension, Social Security and a balance that grew for thirty years.

Which accounts carry a clock, and which don't

The rule follows tax treatment, not the account's name. Anything holding pretax money is on the schedule: traditional IRAs, SEP and SIMPLE IRAs, and employer plans including the 401(k), the 403(b), the governmental 457(b) and old profit-sharing accounts. Roth money is not. A Roth IRA has never required a distribution during the owner's lifetime, and Roth balances inside a workplace plan were brought in line with that treatment, so a Roth 401(k) no longer forces a withdrawal either.

Two carve-outs matter in practice. If you are still working past the start age and do not own more than 5% of the business, you can usually delay distributions from that employer's plan until you actually retire — but only that plan. An IRA does not care whether you are working, and neither does a plan you left behind at a former job, which is why a rollover decision is worth making deliberately before the clock starts rather than discovering it afterward. The mechanics of moving a workplace balance are covered in the 401(k) guide.

Inherited accounts are a separate regime that reuses the same vocabulary. Most non-spouse beneficiaries must empty an inherited account within ten years of the original owner's death, and where the owner had already begun distributions, annual withdrawals continue inside that ten-year window rather than waiting for the end of it. Same term, different rulebook — do not reason from your own RMD to an inherited one.

The divisor is the whole mechanism

The arithmetic is deliberately plain. Take the account balance on the last day of the prior year, divide by a factor read off a published table, and the result is that year's minimum. The factor — the divisor — is a life-expectancy number, and for nearly everyone it comes from the Uniform Lifetime Table. The exception is an owner whose sole beneficiary is a spouse more than ten years younger, who uses a joint-life table instead; the divisor is larger and the required withdrawal correspondingly smaller.

Two properties of that design are worth internalizing. The required withdrawal rate is simply the reciprocal of the divisor, so a divisor of 25 is a 4% withdrawal and nothing more complicated than that. And the divisor falls by roughly one each year, which means the required share of the account rises every year for the rest of your life, and rises faster the older you get. A schedule built to drain an account over a remaining lifetime behaves exactly like one.

Three years of the arithmetic

Assume an $800,000 pretax balance at the first year-end that counts, illustrative divisors of 26.5, 25.5 and 24.6, and 6% growth on whatever stays invested after each withdrawal. The exact factors come from the published table; the shape is what matters.

The balances chain: $800,000 less the first withdrawal leaves $769,811, which grows 6% to $816,000; that year's $32,000 leaves $784,000, which grows to $831,040. Over the two years the account gained 3.9% while the required dollar amount rose almost 12%. The divisor did that, not the market. Run your own balance through the RMD calculator and the same pattern shows up in your numbers.

Required withdrawal rate as the divisor shrinks

	Required withdrawal rate as the divisor shrinks
Divisor 26.5	3.8%
Divisor 20.2	5.0%
Divisor 16.0	6.3%
Divisor 12.2	8.2%
Divisor 8.9	11.2%

The required rate is the reciprocal of the divisor. Illustrative factors spanning the early to late range of a lifetime table; the published table governs the actual figures.

Set that curve beside the withdrawal rate a portfolio can sustain — the 4% rule and its descendants — and the divergence is the point. In the early years the minimum sits below any reasonable spending rate, so the RMD is a tax event and nothing else. Decades later it exceeds what most planners would call sustainable, which is fine, because by then the schedule is emptying an account rather than funding a forty-year retirement.

The first year has two deadlines

The first distribution, and only the first, can be deferred to April 1 of the following year. The second is still due by December 31 of that same year, so deferring means two taxable distributions land in one calendar year, on top of whatever else that year brings. It is worth doing only when the later year's income is genuinely lower — a retirement mid-year, a sold business, a delayed pension start. Absent one of those, taking the first one on time keeps the income in separate brackets.

Run your numbersRMD calculator→

What you can pool, and what you can't

Aggregation rules trip up people with several accounts. IRA minimums are calculated account by account, but the total may be withdrawn from any one IRA or any combination of them — convenient when one account holds cash and another holds something you would rather not sell. Balances in 403(b) plans aggregate the same way, but only among themselves. Employer plans do not: each 401(k) and each 457(b) must pay its own minimum out of its own assets. Someone who kept three old workplace plans owes three separate distributions, and satisfying all three from the largest one leaves two shortfalls that nobody flags until a form arrives.

Missing one is expensive, and quietly common

The penalty is an excise tax on the shortfall — 25% of what should have come out and did not — reduced to 10% if the missed amount is withdrawn and the correction filed within the statutory correction window. Where the failure was a reasonable error and was promptly fixed, a waiver can be requested with the explanation attached to the return.

The usual cause is not defiance but bookkeeping: a forgotten rollover IRA at a former custodian, an inherited account nobody set a reminder for, a plan that sent its notice to an old address. Custodians will calculate and often automate the distribution for accounts they can see. They cannot see the ones they do not hold, which makes a one-page inventory of every retirement account, and which family it belongs to for aggregation, the single most protective thing to keep.

The charitable transfer is the efficient version

From age 70½, an IRA owner can direct money from the IRA straight to a qualifying charity. Up to an inflation-adjusted annual cap, that transfer counts toward the year's required distribution and is excluded from income entirely — it never appears in adjusted gross income at all. That is materially better than withdrawing and then deducting the gift, because income drives more than the tax bill: how much of your Social Security benefit is taxable, Medicare premium surcharges, and every other threshold keyed to income. A deduction cannot walk those back.

Two mechanical conditions. It must be a direct transfer from custodian to charity, never a check that passes through your account first, and it works from IRAs, not from workplace plans — money in a 401(k) has to be rolled to an IRA before it qualifies.

Shrink the base before the clock starts

The most effective work on RMDs happens years before the first one. Between the last paycheck and the start age there is usually a stretch of unusually low income: no salary, Social Security perhaps deferred, and no distributions yet required. Converting pretax money to Roth during that window — deliberately filling the top of a low bracket and paying the tax now — reduces the balance the divisor will act on later and moves the future growth into an account with no clock at all. The Roth conversion calculator shows how much fits below the next bracket edge, and the conversion ladder covers sequencing it across several years.

Two consequences make this worth more than the headline tax saving. A surviving spouse files as a single taxpayer on roughly half the bracket width while inheriting most of the same income, so a large pretax balance is a tax problem that gets worse at the worst moment. And Medicare surcharges are cliffs, not slopes, assessed on income from two years earlier — one oversized distribution can raise a premium long after the money is gone. Modelling the whole sequence, rather than one year at a time, is what the drawdown planner is for.

The goal is not a small tax bill this year. It is a flat one across all of them, which usually means voluntarily recognizing income earlier than required so that less of it is recognized involuntarily later.