I'm 5 years retired and over 72. I found a formula to know what tax bracket I'm in. I found a formula to know what amount of RMD I need to take each year. I cannot find a formula that tells me what percentage needs to be withheld for federal taxes from the RMD that I take in a lump sum each October. The custodian (not past employer) of my RMD funds doesn't offer advice on this and says it is up to me to decide. I chose 10%, but won't know until taxes are filed if it is too much or too little. Is there a formula for this?
