How to Calculate Your Required Minimum Distribution (RMD)

A Required Minimum Distribution (RMD) is the amount the IRS requires you to withdraw each year from certain retirement accounts once you reach a specific age. Understanding how to calculate it matters because missing or miscalculating your RMD can result in a significant tax penalty—even if you didn't need the money.

What Triggers an RMD? 📋

RMDs apply to most tax-deferred retirement accounts, including:

• Traditional IRAs (SEP-IRAs and SIMPLE IRAs too)
• 401(k)s, 403(b)s, and 457(b) plans
• Inherited IRAs (with different rules depending on your relationship to the original owner)

Roth IRAs are generally exempt during the original account holder's lifetime, which is one key distinction that affects your planning.

The age at which RMDs begin has shifted in recent years due to tax law changes, so your specific starting age depends on when you were born. This is the first variable you'll need to confirm with your financial institution or tax professional.

The Core Calculation: Three Key Factors

Your RMD amount relies on three pieces of information:

1. Your account balance as of December 31 of the previous year This is typically the fair market value on that specific date. Your custodian (the bank, brokerage, or plan administrator) will provide this figure on your year-end statement.

2. Your age (or your life expectancy factor) The IRS publishes life expectancy tables that assign a divisor based on your age. A younger person has a higher divisor (meaning a smaller distribution), while an older person has a lower divisor (meaning a larger distribution). The three main tables are the Uniform Lifetime Table (used most often), the Single Life Expectancy Table, and the Joint Life and Last Survivor Expectancy Table.

3. The IRS divisor for your age This is where the calculation happens: divide your account balance by the divisor that matches your age according to the correct IRS table.

The formula is simple:

Which Table Applies to You?

This depends on your situation:

Using the wrong table is a common mistake, so double-check which applies to your circumstances.

What Different Situations Look Like

Someone at the earliest RMD age might have an account worth $500,000 and a divisor around 27–28, resulting in an RMD in the $18,000–$19,000 range.

Someone significantly older might have the same balance but a divisor around 18–20, resulting in an RMD in the $25,000–$28,000 range.

Someone with multiple accounts (say, three separate IRAs) must calculate the RMD for each account separately, but can withdraw the total amount from any one or combination of those accounts—another rule many people misunderstand.

Why the Details Matter 📌

Small errors—using the wrong table, pulling from the wrong account type, or missing the deadline—can trigger a 25% penalty on the amount you should have withdrawn (recently reduced from 50% under the SECURE 2.0 Act, but still substantial). The IRS can waive this penalty if you can show reasonable cause, but prevention is far easier than correction.

How to Get Your Numbers

• Contact your financial institution directly; many custodians calculate RMDs for you or provide the account balance needed.
• Use IRS Publication 590-B, which includes all three life expectancy tables and detailed examples.
• Check with a tax professional or financial advisor if your situation involves inherited accounts, multiple account types, or spousal beneficiary rules—these situations have special rules that vary.

The calculation itself is straightforward arithmetic, but getting the inputs right depends on your specific age, account structure, and family circumstances.