Withholding too little taxes or paying too little in estimated taxes is an easy mistake to make. Learn how to avoid a tax penalty for under-withholding taxes.

If you already filed your 2018 tax return and paid the underpayment penalty, you can request a refund of the penalty by filing Form 843. Include "80% Waiver of estimated tax penalty" on line 7.

Here’s a wake-up call for millions of Americans who pay some or all their income taxes quarterly rather than through paycheck ...

The penalty for underpayment works ... making an estimated tax payment by January 15, 2010, can reduce the penalty you’ll owe when you file your return. Use Form 1040ES to make the payment.

The underpayment penalty is capped at 25% of ... If you owe more than $50,000, you have to apply for an installment plan using IRS Form 9465. Plans must be completed within seven months or less ...