Essentially the same scenario for us, including taking a lump sum RMD in December. Our annual income ended up higher than I had expected so we owed more tax, and therefore had to pay the "failure for proper estimated tax" penalty that TurboTax Deluxe calculated to be $332. Okay, whatever, but then last week we were refunded $297.10 by the IRS because they said that our penalty should have only been $24.90.
We have Federal tax withheld monthly from pensions, and also have a chunk of money taken out of the December RMD for Federal tax.
