1. the dates are meant to reflect your Q1 ES due 4/15 needs to cover your liability for Q1 thru 3/31, and so on
2. not clear what problem you are having here - the Q4 annualization is based on your full liability/payments for the year so the multiplier is just 1x. I just went thru the AI process for a December Roth conversion matched with a Q4 ES in January, and my final penalty was $1.
