@Lani6 Just want to make sure you are clear, you said.....As our RMD will more than cover the tax due (based on 110% of last year's return).... You mean the withholding on the RMD? The RMD is the total distribution. Just the tax withholding will cover the tax due on your return. So the amount they take out of your RMD will be more than 110% of last year's tax?
I think the withholding is like withholding from your paychecks. It is assumed to be paid evenly during the year if it needs to figure a penalty for underpaying your taxes. @dmertz can you help explain it?
Maybe Form 2210 will help.
https://www.irs.gov/pub/irs-pdf/f2210.pdf
IRS Form 2210 Instructions
https://www.irs.gov/pub/irs-pdf/i2210.pdf
