Tax Extension Deadline Calculator
Missing a tax deadline can cost you thousands in penalties. Use this calculator to see every deadline for your entity type — original filing, extension, and estimated payments — with a live countdown.
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Tax Extension Deadline Calculator
Know your deadlines. Avoid penalties.
Enter an amount to see penalty estimates if late
Disclaimer: This calculator provides estimates based on standard IRS deadlines. Special circumstances (disaster relief, military service, overseas filing) may change your deadlines.
Understanding Tax Extensions
A tax extension gives you more time to file your return — but it does not give you more time to pay. This is the single biggest misconception taxpayers have about extensions, and it's why people end up with unexpected penalty bills.
Extension vs. Payment: The Critical Difference
When you file Form 4868 (individuals) or Form 7004 (businesses), you get an automatic extension of time to file — typically 6 months. But the IRS still expects you to estimate your tax liability and pay it by the original deadline. If you owe money and don't pay by the original due date, you'll face:
- Late payment penalty (0.5%/month) — Accrues on the unpaid balance each month, up to 25% maximum.
- Interest (~8% annually for 2025) — Compounds daily on the unpaid balance plus penalties.
The good news: if you file an extension, you avoid the much steeper late filing penalty (5%/month, up to 25%). So even if you can't pay in full, filing an extension still saves you money.
Filing Deadlines by Entity Type
Not all businesses file at the same time. Here's the breakdown:
- S-Corps & Partnerships (March 15) — These pass-through entities file early so owners get their K-1s in time to file personal returns. Extension goes to September 15.
- Individuals & C-Corps (April 15) — Standard filing deadline. Individual extension goes to October 15; C-Corp extension also goes to October 15.
- Trusts & Estates (April 15) — File Form 1041. Extension goes to September 30 (5.5-month extension).
When Deadlines Fall on Weekends
If a deadline falls on a Saturday, Sunday, or federal holiday, it moves to the next business day. For example, if March 15 falls on a Saturday, the S-Corp deadline shifts to Monday, March 17. Our calculator handles these adjustments automatically.
Frequently Asked Questions
Does a tax extension give me more time to pay?
No. An extension only gives you more time to FILE your return. Payment is still due by the original deadline. If you owe taxes and don't pay by the original due date, you'll accrue late payment penalties and interest even if you filed an extension.
How do I file a tax extension?
Individuals file Form 4868 by April 15. Businesses file Form 7004 by their respective due date (March 15 for S-Corps/partnerships, April 15 for C-Corps). You can file electronically through IRS Free File or your tax software, or mail the form.
What is the penalty for filing late without an extension?
The late filing penalty is 5% of unpaid taxes per month, up to 25%. If you also don't pay on time, there's an additional 0.5%/month late payment penalty. Filing an extension eliminates the filing penalty, but you still owe the payment penalty on any balance due.
Does Texas have a separate extension?
Texas has no state income tax, so there's no state tax extension needed. However, if your entity owes Texas franchise tax (most LLCs and corporations), that return is due May 15 with an automatic extension to November 15.
Can I still contribute to my IRA after filing an extension?
IRA contribution deadlines are based on the original filing deadline (April 15), not the extended deadline. An extension does NOT give you extra time to make IRA contributions. However, SEP-IRA contributions can be made up to the extended due date.
Need help filing your extension?
Don't risk penalties by missing a deadline. We file extensions for DFW business owners every day — and can help you estimate your payment to minimize penalties.
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