Estimated tax payment is required to be deposited by the taxpayer generally if the tax payable after reduction of tax credits and withholding tax is $1000 or more. Internal Revenue Code §6654 is regarding the failure by an individual to pay properly estimated tax. It provides that a person will have to pay an additional dollar (basically interest charged by IRS) in case he fails to pay estimated tax in time. So , you may regard that additional payment on account of your failure to pay the estimated tax as a penalty!Read More »FAQs on Penalty for Underpayment of Estimated Tax
estimated tax payments form
Calculator for Form 2100 gives you an instant finding if you need to fill Form 2210 which is needed if you have made underpayment of estimated tax to the extest that additional tax needs to be paid by you.