Taxes & Rules

RMD Calculator, Explained: What the IRS Formula Is Actually Doing

ALBy The AnnuaLife Team12 min read · Updated September 20, 2026

An RMD calculator divides your retirement account balance from December 31 of last year by a single divisor from the IRS Uniform Lifetime Table, chosen by the age you reach this year. That is the whole formula. A 75-year-old uses a divisor of 24.6, so a $500,000 balance produces a required withdrawal of about $20,325.

Every year the IRS hands out the same ruler. It does not care what you paid for your investments, what your tax bracket is, or whether you need the money. It asks one question, your age, gives you one number, and tells you to measure your account with it.

That is what makes required minimum distributions unusual among tax rules. Almost everything else in the tax code adjusts to your circumstances. This one does not. The only two facts that enter the calculation are a balance and an age, which is why a calculator can produce the answer in about four seconds and why the number is not negotiable once you know it.

What is negotiable is everything around it: which account you take it from, when in the year you take it, what you do with the money afterward, and whether you take steps now that make future rulers measure less. This guide walks the formula, shows exactly what the AnnuaLife tool asks and returns, and covers the traps that catch people in the first year. It is general education, not tax advice.

01Find the balance

Your IRA or plan value on December 31 of last year. Not today’s balance, not an average.

02Find your divisor

Look up the age you turn during this calendar year in the IRS Uniform Lifetime Table.

03Divide

Balance divided by divisor equals the amount you must withdraw this year. Withdraw at least that much by the deadline.

What is an RMD calculator actually calculating?

The fraction of your tax-deferred savings the IRS requires you to withdraw and pay tax on this year. Required minimum distributions exist because traditional IRAs and 401(k)s were funded with money that has never been taxed. The deferral was never meant to be permanent, so at a certain age the government starts requiring a slice each year.

The divisor is a life expectancy factor. Dividing by 24.6 is the same as withdrawing about 4.07 percent of the balance, and as the divisor shrinks with age the required percentage climbs. The AnnuaLife calculator shows you that percentage directly, labeled the withdrawal rate, which is a useful thing to see because it reframes an intimidating dollar figure as a rate you can plan against.

Worked example. A 75-year-old with $500,000 in a traditional IRA on December 31 of last year uses a divisor of 24.6 from the IRS Uniform Lifetime Table.

$500,000 divided by 24.6 equals about $20,325 for the year, a withdrawal rate of roughly 4.07 percent. A 73-year-old with $400,000 uses 26.5, producing about $15,094, or about 3.77 percent. Both are minimums. You may always take more, and any amount above the minimum does not reduce next year’s requirement.

What does the AnnuaLife RMD calculator ask for?

Two inputs, which is all the formula needs. The RMD calculator asks for your prior year-end account balance, described on the page as your IRA or 401(k) value on December 31 of last year, and your age at the end of this year, described as the age you turn during 2026.

That second field is where most people slip. It is not your age today and it is not your age on your birthday last year. It is the age you will have reached by December 31 of the distribution year, so someone turning 75 in November uses the 75 divisor for the whole year.

This year’s required minimum. The dollar amount you must withdraw, shown as soon as both fields are filled.
IRS divisor. The exact life expectancy factor used, so you can check the arithmetic yourself rather than trusting a black box.
Withdrawal rate. The required amount expressed as a percentage of the balance, which is the number worth watching year over year.
Save this scenario. A free My AnnuaLife account keeps the scenario so you can pick it back up on any device.

The page states that the calculator uses the IRS Uniform Lifetime Table and shows the exact divisor behind the number, and that the result is an educational estimate rather than tax advice. It also publishes the divisor table itself further down the page, along with the rules and a set of FAQs.

Showing the divisor is the whole point. A number you cannot check is a number you cannot argue with.

The AnnuaLife Team

Which divisor is yours?

The one that matches the age you reach during this calendar year, taken from the IRS Uniform Lifetime Table, which is Table III in IRS Publication 590-B. Here are the factors most readers need, along with what each one implies as a withdrawal rate.

Age reached this year	IRS divisor	Required withdrawal rate	On a $500,000 balance
73	26.5	3.77%	$18,868
75	24.6	4.07%	$20,325
78	22.0	4.55%	$22,727
80	20.2	4.95%	$24,752
85	16.0	6.25%	$31,250
90	12.2	8.20%	$40,984

Source: IRS Uniform Lifetime Table (Table III, IRS Publication 590-B). Withdrawal rates and dollar figures are calculated from those divisors. The full table by single year of age sits on the RMD calculator page and in our 2026 RMD table guide.

Two situations use a different table entirely, and using the Uniform Lifetime Table for either produces the wrong number.

A spouse more than 10 years younger who is your sole beneficiary. You use the Joint Life and Last Survivor Expectancy Table instead, which produces a larger divisor and therefore a smaller required withdrawal.
An account you inherited. Inherited IRAs follow their own rules, including the Single Life Table and the 10-year distribution window that applies to many non-spouse beneficiaries. See RMDs from an inherited IRA before calculating anything.
An account already annuitized. Once an IRA is converted into a stream of annuity payments, the payments themselves generally satisfy the requirement for that contract, and the divisor math no longer applies to it. Our guide to annuity RMD rules covers the interaction.

When do RMDs start, and what is the April 1 trap?

Under SECURE 2.0, required minimum distributions begin at age 73 if you were born between 1951 and 1959, and at age 75 if you were born in 1960 or later. Your very first distribution has a special deadline, and that special deadline is where an avoidable tax bill gets created.

Required beginning date

For your first RMD only, the deadline is April 1 of the year after the year you reach your RMD age. Every subsequent year’s distribution is due by December 31.

The stacking trap

If you use that April 1 extension, you take two required distributions in the same calendar year: the delayed first one and the current year’s, due that December 31. Both are taxable income in the same year, which can push you into a higher bracket, raise how much of your Social Security is taxable, and affect income-related Medicare premium surcharges.

The usual answer

Most people take the first distribution by December 31 of the first year instead, spreading two years of income across two tax years. The extension exists for a reason, but it is a choice, not a default.

There is no partial credit for timing within the year. You can take the whole amount in January, spread it monthly, or take it in December. What matters to the IRS is that the full required amount left the account by the deadline.

Which accounts does this apply to, and can you combine them?

Traditional IRAs, SEP and SIMPLE IRAs, 401(k)s, 403(b)s, and most other tax-deferred employer plans. Roth IRAs have no required distributions during the original owner’s lifetime, and SECURE 2.0 removed lifetime RMDs from designated Roth accounts in employer plans beginning in 2024.

The aggregation rules are the part people get wrong, and getting them wrong is what triggers penalties.

Account type	How the RMD is calculated	Where you can take it from
Traditional, SEP, SIMPLE IRAs	Separately for each account	Any one IRA, or any combination, as long as the total is met
403(b) accounts	Separately for each account	Any one 403(b), or a combination of 403(b)s
401(k) and most other plans	Separately for each plan	Each plan must pay its own. No combining
Inherited IRAs	Under separate beneficiary rules	Never combined with your own IRAs

One more exception is worth knowing. If you are still working past your RMD age, are not a 5 percent owner of the business, and your employer’s plan allows it, you may be able to delay distributions from that employer’s plan until you retire. It never applies to IRAs, and it never applies to old plans left behind at former employers.

What happens if you miss an RMD?

An excise tax, and it is smaller than it used to be. SECURE 2.0 reduced the penalty for a missed required distribution from 50 percent of the shortfall to 25 percent, and to 10 percent if you correct the shortfall within the correction window the law allows. The correction is reported on IRS Form 5329, and the IRS may waive the tax entirely if the shortfall was due to reasonable error and you take steps to fix it.

Take the missed amount as soon as you find the error, in a separate transaction so it is easy to document.
File the form for the year of the shortfall rather than quietly rolling it into a later year.
Check every account, not just the largest one. Missing a small 401(k) from a former employer is a common way this happens.
Ask your custodian to set an automatic distribution for future years. Most will calculate and send it on a schedule you choose.

Can you reduce future RMDs?

Yes, though every method has a cost, and the ones worth considering are structural rather than clever. The two most common are worth understanding before you talk to anyone.

Qualified charitable distributions

If you are 70 and a half or older, you can direct money from an IRA straight to a qualifying charity, and that transfer can count toward your required distribution while staying out of your taxable income. There is an annual limit that the IRS indexes, so check the current year’s figure before planning around it.

A QLAC

A qualified longevity annuity contract lets you move a limited amount of IRA or plan money into a deferred income annuity whose value is excluded from the balance used to calculate RMDs, with income required to begin no later than age 85. The premium limit is $210,000 for 2026 under IRS Notice 2025-67. Guarantees depend on the claims-paying ability of the issuing insurer, and QLACs are not FDIC insured. See QLACs and QLAC RMD rules.

Roth conversions

Moving traditional money to a Roth IRA removes it from future RMD calculations, at the cost of paying tax on the converted amount in the year of conversion. Whether that trade works depends on your bracket now against your expected bracket later, which is a tax professional’s question, not a calculator’s.

How soon are you retiring?

Within 5 years Within 10 years Already retired Not sure yet

Next step

There is also a question the calculator quietly raises: what do you do with the money once it is out? The requirement is that you withdraw it and pay tax on it, not that you spend it. Some retirees reinvest it in a taxable account. Others use required distributions to fund a guaranteed income stream so the withdrawal turns into a paycheck rather than a chore, which is what the calculator’s own prompt is pointing at when it mentions turning the withdrawal into income. Our guides to income annuities and to how much a million dollars pays cover what that looks like in dollars.

Moving forward

The ruler is the same for everyone, and once you know your divisor you know your number. Run yours on the RMD calculator, which will show the required amount, the exact IRS divisor behind it, and what that works out to as a withdrawal rate. Save the scenario and you can compare years without redoing the arithmetic.

The part worth a conversation is everything the ruler does not measure: which account to draw from, whether to take the first distribution early to avoid stacking two into one year, whether a QLAC or a conversion changes the picture, and what the money should do next. A Certified Annuity Advisor can walk those options with you, and anything touching your tax return should also be reviewed by a tax professional. See how annuities are taxed for the wider picture.

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Frequently asked questions

How do you calculate an RMD for 2026?

Divide your account balance as of December 31, 2025 by the divisor for the age you reach during 2026, taken from the IRS Uniform Lifetime Table. For example, a $500,000 balance at age 75 uses a divisor of 24.6 and produces about $20,325. The AnnuaLife RMD calculator does this and also displays the divisor and the resulting withdrawal rate so you can verify the math.

What is the Uniform Lifetime Table?

It is the IRS life expectancy table most account owners use to calculate required distributions, published as Table III in IRS Publication 590-B. Each age maps to a divisor: 26.5 at 73, 24.6 at 75, 20.2 at 80, 16.0 at 85. The divisor shrinks as you age, so the required percentage of your balance rises from about 3.77 percent at 73 to about 6.25 percent at 85.

At what age do RMDs start?

Age 73 if you were born between 1951 and 1959, and age 75 if you were born in 1960 or later, under the SECURE 2.0 rules. Your first distribution can be delayed until April 1 of the following year, but doing so means taking two required distributions in the same calendar year, which stacks the income. Every distribution after the first is due by December 31.

Which balance do I use?

The fair market value of the account on December 31 of the prior year. Market movements during the current year do not change the required amount, which is why a required distribution can feel large after a down year and small after a strong one. Your custodian reports that year-end value and will usually calculate the required amount for you as well.

Can I take my RMD from just one account?

It depends on the account type. Required amounts are calculated separately for each traditional, SEP, or SIMPLE IRA, but the total may be withdrawn from any one of them or any combination. The same flexibility applies within 403(b) accounts. A 401(k) or similar employer plan must distribute its own required amount separately, with no combining across plans.

What is the penalty for missing an RMD?

An excise tax of 25 percent of the amount you failed to withdraw, reduced to 10 percent if you correct the shortfall within the window SECURE 2.0 allows. The correction is reported on IRS Form 5329, and the IRS can waive the tax when the shortfall resulted from reasonable error and is promptly corrected. Take the missed amount immediately and document it as a separate transaction.

Do Roth accounts have RMDs?

Roth IRAs have no required distributions during the original owner’s lifetime. Designated Roth accounts inside employer plans no longer have lifetime RMDs either, following a SECURE 2.0 change effective in 2024. Beneficiaries who inherit Roth accounts do face distribution requirements, which follow the inherited-account rules rather than the Uniform Lifetime Table.

Can an annuity reduce my required distributions?

A QLAC can. Money moved into a qualified longevity annuity contract is excluded from the balance used to calculate RMDs, up to a premium limit of $210,000 for 2026 under IRS Notice 2025-67, with income required to begin by age 85. The trade is liquidity, since the premium is committed to a deferred income contract, and any guarantee depends on the issuing insurer’s claims-paying ability. QLACs are not FDIC insured. This is general education, not tax advice.