Thanks Opus 17, very helpful info and suggestions.
SS aside, I didn't realize that the IRS expects income that is mostly received in December to be paid out evenly throughout the year. I haven't been doing that, but instead withholding my expected tax burden from the year-end IRA distribution. Yet haven't been assessed a penalty. I guess I've been lucky. (Although other factors may have partially contributed, including paying about 10% withholding on a modest monthly pension I've had for awhile; and -- maybe half the time -- ending up paying withholding that exceeds my previous year's total tax.)
EDITED to correct a misstatement.
