How to Use IRS Mortality Tables to Calculate RMDs

To use IRS mortality tables to calculate RMDs, you divide your retirement account balance as of December 31 of the prior year by the life expectancy factor listed next to your current age in the correct IRS table. For most account owners, that table is the Uniform Lifetime Table in Publication 590-B. The result is the minimum amount you must withdraw for the year.

The math takes about ten seconds. The work is in choosing the right table, using the right balance, and knowing the deadline.

Pick the Right Table First

Publication 590-B contains three separate life expectancy tables, and each produces a different distribution period. Using the wrong one means withdrawing more than you need to (and paying more tax than you owe) or withdrawing too little and triggering a penalty.

The Uniform Lifetime Table (Table III) is the default for account owners taking RMDs during their own lifetime. It assumes a hypothetical beneficiary ten years younger than you. Use it if you’re unmarried, if your spouse is your beneficiary but not more than ten years younger, or if your beneficiary is anyone other than your spouse.¹
The Joint Life and Last Survivor Table (Table II) applies only when your spouse is your sole beneficiary and is more than ten years younger than you. It produces a longer distribution period and a smaller required withdrawal than the Uniform Lifetime Table.¹
The Single Life Expectancy Table (Table I) is used mainly by beneficiaries who inherited a retirement account and qualify to stretch distributions over their own life expectancy.

If you’re a married account owner whose spouse is much younger, check whether the Joint Life table applies before defaulting to Uniform Lifetime. Skipping that check means accelerating the tax hit on money that could keep growing tax-deferred.

Run the Calculation

Three inputs, one division problem.

Start with your account balance as of December 31 of the prior year, taken from the year-end statement your financial institution or plan administrator sends you. Find your age as of your birthday in the current year. Look up the corresponding factor in the applicable table.² Divide.

Uniform Lifetime Table factors for the ages when most people begin RMDs:

Age 73: 26.5
Age 74: 25.5
Age 75: 24.6
Age 76: 23.7
Age 77: 22.9
Age 78: 22.0
Age 79: 21.1
Age 80: 20.2

A worked example: you’re 73 and your traditional IRA held $500,000 on December 31 of last year. Divide $500,000 by 26.5 and your RMD for the year is about $18,868. At age 80 with the same balance, the factor of 20.2 produces an RMD of roughly $24,752. The factor shrinks as you age, so the required withdrawal grows even when the balance holds steady. You redo the calculation every year, using that year’s factor and the prior year-end balance.¹

Using the Joint Life and Last Survivor Table works the same way, but the factor sits at the intersection of your age and your spouse’s age as of each person’s birthday in the current year. That factor will be larger than the Uniform Lifetime figure, which reduces the required withdrawal.

The distribution is generally reported on Form 1040 as ordinary income and taxed at your ordinary rate.³

When the RMD Is Due

RMDs must generally be taken by December 31 of each year. There’s one exception, and it has a catch. For your very first RMD, you can delay the withdrawal until April 1 of the following year. But your second RMD is still due December 31 of that same year, so delaying the first one means two full RMDs land on the same tax return, which can push you into a higher bracket.³

Miss an RMD or take less than required, and the IRS charges a 25% excise tax on the shortfall. If your RMD was $20,000 and you withdrew $12,000, the penalty applies to the $8,000 difference. The rate drops to 10% if you fix the shortfall during the correction window, which generally runs until the end of the second taxable year after the year you missed the distribution. You report the shortfall and the corrected tax on Form 5329 filed with your return.⁴ The IRS can also waive the penalty entirely if you show the shortfall came from reasonable error and you’ve taken steps to fix it.³

What Age Triggers the Requirement

Under current law, most people must begin taking RMDs in the year they turn 73. That age applies to anyone born between 1951 and 1959.³ If you were born in 1960 or later, the starting age moves to 75 beginning in 2033.

Accounts That Skip the Calculation

Not every retirement account requires the mortality table math while you’re alive. Roth IRAs have never been subject to lifetime RMDs, and starting in 2024, designated Roth accounts in workplace plans such as 401(k)s and 403(b)s are also exempt.³ After the Roth account owner dies, beneficiaries generally do face distribution requirements.

A separate exception covers workplace plans if you’re still employed. Participants in an employer-sponsored plan can delay RMDs from that plan until the year they actually retire, as long as they don’t own 5% or more of the business.³ This applies only to the plan at your current employer. Old 401(k)s from former employers and any traditional IRA still start at age 73 regardless of whether you’re working.

Inherited Accounts Use Different Rules

If you inherited a retirement account, the mortality table you use and whether you use one at all depend on when the original owner died and who you are to them.

For accounts whose owners died in 2020 or later, most non-spouse beneficiaries must empty the entire inherited account by December 31 of the year containing the tenth anniversary of the owner’s death.¹ If the original owner died before their required beginning date, no annual distributions are required during the ten-year window; you can take a lump sum in year ten or spread withdrawals however you like. If the owner died after their required beginning date, the rules are more complex and may require annual distributions during the ten years.

Certain beneficiaries, called eligible designated beneficiaries, still qualify to stretch distributions over their own life expectancy using the Single Life Expectancy Table:

A surviving spouse of the deceased account owner
A minor child of the deceased account owner, until reaching the age of majority, when the 10-year clock starts
Disabled or chronically ill individuals
Beneficiaries who are not more than 10 years younger than the deceased owner

Adult children, siblings, friends, and other non-spouse beneficiaries who don’t fit those categories fall under the 10-year rule.⁵ Older guidance describing lifetime stretch treatment for these beneficiaries still circulates and no longer reflects the current rule.

If You Have More Than One Account

Own multiple traditional IRAs? Calculate the RMD separately for each account, then take the combined total from any one IRA or split it across several however you want.¹ The flexibility lets you draw down one account while leaving others alone.

That rule does not extend to 401(k)s. Each 401(k) requires its own RMD calculation, and the distribution has to come from that specific plan. You cannot satisfy a 401(k) RMD by pulling from an IRA, or the other way around. If you collected 401(k)s at several employers over a career, track each one separately or consolidate before RMDs begin.

1
Internal Revenue Service. Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs)
2
Internal Revenue Service. Retirement Topics – Required Minimum Distributions (RMDs)
3
Internal Revenue Service. Retirement Plan and IRA Required Minimum Distributions FAQs
4
Office of the Law Revision Counsel. 26 USC 4974 – Excise Tax on Certain Accumulations in Qualified Retirement Plans
5
Internal Revenue Service. Retirement Topics – Beneficiary