Tax Extension Balance Due Calculator

Estimate the federal tax balance remaining after withholding, estimated payments, extension payments and other credits. Gather your draft return and payment receipts before using the calculator below. Texas franchise tax is a separate calculation for your business entity.

Example and assumptions

An estimated federal tax liability of $20,000 less $15,000 in payments and credits leaves an estimated $5,000 balance before penalties, interest or other adjustments. An extension gives you additional time to file; it does not extend the original payment deadline.

This tool does not calculate penalties or interest or confirm that every requirement for a valid federal or Texas extension has been satisfied. Use the completed return and the applicable agency rules to confirm your actual balance.

Need help reconciling payments or completing your return? Explore our tax planning services and bookkeeping services, or book a consultation.

Published by Weidner CPA. Firm principal: Edward Weidner, CPA. Updated 2026. Source: IRS Topic 304: Extensions of Time to File.