The IRS systems assume you earn your income equally throughout the year. this might not be the case for realtors, or self-employed folks, or people who have change/lost jobs. Input your income on the F2210 in the quarter you earned it. That way the penalty should be less.
If you are charged a penalty and you don't think you should owe it, there is a First Time Penalty Abatement tool on the irs website. Often if you have not had penalties assessed against you the last 3 years you can get a FTA but you generally have to request it.
