Which form is used to report an underpayment of estimated tax by individuals, estates, and trusts?

The form used to report an underpayment of estimated tax by individuals, estates, and trusts is Form 2210. This form is specifically designed to calculate any penalties that may be owed due to underpayment of estimated taxes throughout the year. It requires the taxpayer to provide information regarding their income and tax liability to determine whether they paid enough through withholding or estimated payments.

Using Form 2210 allows taxpayers to show that they had a valid reason for underpayment and to calculate any potential penalty accurately. It can also be used to request a waiver of the penalty under certain circumstances. Understanding the purpose of this form is essential for taxpayers who find themselves in a situation where they underpaid their taxes and are concerned about penalties.

The other options serve different purposes: Form 4868 is used for requesting an extension to file the federal income tax return; Form 8815 relates to the tax treatment of qualified U.S. savings bonds; and Form W-4 is for employees to indicate their withholding preferences to their employer.