Do I need to determine the RMD for an annuity if Box 2a already shows the taxable amount?

It depends. The plan administrator has the information and does the calculation of the required minimum distribution (RMD) for any and all retirement plans. However, the IRS has information about how to calculate the RMD.

Q4. How is the amount of the required minimum distribution calculated?

Generally, a 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 the IRS publishes in Tables in Publication 590-B, Distributions from Individual Retirement Arrangements (IRAs). Choose the life expectancy table to use based on your situation.

• Joint and last survivor table II - use this table if the sole beneficiary of the account is your spouse and your spouse is more than 10 years younger than you.
• Uniform lifetime table III - use this if your spouse is not your sole beneficiary or your spouse is not more than 10 years younger
• Single life expectancy table I - use this if you are a beneficiary of an account (an inherited IRA)

See the worksheets to calculate required minimum distributions and the FAQ below for different rules that may apply to 403(b) plans.