Generally, an RMD is calculated for each account by dividing the prior December 31 balance of that IRA or retirement plan account by a life expectancy factor that IRS publishes in Tables in Publication 590-B, Distributions from Individual Retirement Arrangements (IRAs). Choose the correct life expectancy table to use based on your situation.
Joint and Last Survivor Table - use this if the sole beneficiary of the account is your spouse and your spouse is more than 10 years younger than you
Uniform Lifetime Table - use this if your spouse is not your sole beneficiary or your spouse is not more than 10 years younger
Single Life Expectancy Table - use this if you are a beneficiary of an account (an inherited IRA)
You can download and complete the appropriate worksheet to calculate your RMD using the table that fits your situation.
Although the IRA custodian or retirement plan administrator may calculate the RMD, the IRA or retirement plan account owner is ultimately responsible for calculating the amount of the RMD.
What if I have more than one IRA or Retirement Account?
An IRA owner must calculate the RMD separately for each IRA that he or she owns, but can withdraw the total amount from one or more of the IRAs. Similarly, a 403(b) contract owner must calculate the RMD separately for each 403(b) contract that he or she owns, but can take the total amount from one or more of the 403(b) contracts.
However, RMDs required from other types of retirement plans, such as 401(k) and 457(b) plans have to be taken separately from each of those plan accounts.
NOTE: If you fail to take your full Required Minimum Distribution (RMD), you will need to complete Part IX of Form 5329.