Should I mark retirement inc as RMD even tho I've been receiving it many years as a divorce agreement?

RMD stands for Required Minimum Distribution. It's the minimum amount of money you're required to take out of your retirement plan once you turn 70 1/2.

RMD rules apply to all employer-sponsored retirement plans such as pensions, profit-sharing, 401(k), 403(b), and 457(b) plans, as well as Traditional IRAs and IRA-based plans such as SEPs, SARSEPs, and SIMPLE IRAs. However, RMDs are not required for Roth IRAs while the owner is still alive.

Your 1099-R issuer is required to follow RMD rules and regulations, so if you received a distribution and you're at least 70 1/2 years young, you can be almost certain you received an RMD. Check with your plan administrator if you're still not sure.