Calculating Required Minimum Distributions?

Hi, I was thinking about this scenario recently:

December 31st, 2035, I turn 70; December 31st, 2036 I’ll be 71. I will always take my RMD before Midnight, December 31st of each year once I begin taking them.

To calculate RMDs from my and my wife’s IRAs (excluding Roth IRA) and my 401K, is the calculation a one-time formula calculation? OR, is the calculation performed each year to account for increases resulting from gains/dividends?

Stay focused now…for example, IF all of my traditional IRAs plus my 401K balances equal $1,000,000, on December 31st 2035 and the following December 31st I plan to begin taking my RMDs, do I calculate my RMD with respect to December 2035 or December 2036?

Is that a one time calculation and I’ll never have to calculate it again? OR, do I recalculate my RMD every year, with respect to my balances on December 31st of the current year or the previous year?

Also, if my RMD is (hypothetically) $40,000 but I "earn" $60,000 in gains/dividends, can I withdraw only the $40,000 and allow the remaining $20,000 to continue working for me within my accounts?

OR do I need move that $20,000 into another account (i.e., savings, money market, etc.) so it isn’t "co-mingling" and "tainting" my accounts? In other words, are my traditional IRAs and 401K balances allow to grow with gains/dividends even if the gains/dividends are greater than the RMD?

Perhaps this is a confusing question but I am constantly thinking about my retirement, and I wanted to see what I can expect regarding how to manage my RMDs and gains/dividends. Thanks!

Why not get it from the horses mouth? IRS Publication 575 applies to 401(k) and 590 applies to IRAs. It has to be calculated annually, but it does not have come from all accounts, you can take the required amount from one or more of the accounts that the same grand total calculation applies to. For example for traditional IRAs see

Note that you can still do IRA to Roth IRA conversions if you want to (my mom is still doing that at age 80). But you cannot do that with required minimum distributions, just an amount beyond that.