Understanding the April 15 Tax Deadline: What’s Due and How to File an Extension

Adam Tahir
Mar 20
3 min read

As Tax Day approaches each year, April 15 is one of the most important dates on the calendar for individuals and many businesses. Missing this deadline can lead to penalties, interest, and missed opportunities for deductions or refunds.

In this blog post, we’ll walk through:

What tax filings are due by April 15
Who needs to file
How to file for an extension
What’s not extended (hint: it's the payment)

What’s Due on April 15, 2025 (for Tax Year 2024)?

Form 1040 – Individual Income Tax Return

This is the most common filing due on April 15.
It includes federal income tax for individuals, along with related forms like:
- Schedule C (self-employed business income)
- Schedule E (rental and pass-through income)
- Schedule SE (self-employment tax)
If you owe taxes and do not pay by April 15, penalties and interest begin accruing—even if you file for an extension.

Form 4868 – Extension to File Individual Return

Filing Form 4868 gives you an automatic 6-month extension to October 15, 2025 to file your Form 1040.
Important: This is only an extension to file, not to pay.
You must estimate and pay any taxes owed by April 15 to avoid penalties.

Form 1120 – C Corporation Tax Return

Calendar-year C corporations must file Form 1120 by April 15.
If on a fiscal year (not ending December 31), the return is due on the 15th day of the fourth month after year-end.
Corporations can request an automatic 6-month extension using Form 7004.

Form 5498-ESA – Education Savings Account Contributions

Due from trustees to report contributions to Coverdell ESAs, but it may be helpful for individuals who contributed to these accounts by the April 15 deadline.

Contributions to IRAs and HSAs

April 15 is also the last day to make contributions for the 2024 tax year to:
- Traditional and Roth IRAs
- Health Savings Accounts (HSAs)
- SEP IRAs (unless extended)

First Estimated Tax Payment – Form 1040-ES

If you’re self-employed or have significant non-W2 income, the first quarterly estimated tax payment for 2025 is also due on April 15.
Missing estimated payments can result in underpayment penalties.

What’s NOT Due on April 15?

Form 1065 (Partnership Returns) and Form 1120S (S Corporation Returns) are typically due March 15 for calendar-year businesses.
Extended due dates for those forms: September 15, 2025.
State returns often follow April 15, but deadlines vary by state.

How to File an Extension (And Why You Might Want To)

For Individuals (Form 1040):

File Form 4868 electronically or by mail.
You don’t need to explain why you’re requesting an extension.
You’ll get an automatic 6-month extension, moving your deadline to October 15.

For C Corporations (Form 1120):

File Form 7004 to get a 6-month extension (until October 15).
You still must pay your estimated tax liability by April 15.

Important Note: Extensions Don’t Extend Payment Deadlines

Many taxpayers mistakenly believe that filing an extension also defers tax payments.
In reality, if you don’t pay your taxes by April 15, the IRS will charge:
- Late payment penalties (typically 0.5% per month)
- Interest on unpaid balances
It’s recommended to pay as much as you reasonably estimate when filing the extension.

How to Make a Payment to the IRS by April 15

Even if you're not ready to file your return, you can pay your estimated taxes through:

IRS Direct Pay: https://directpay.irs.gov
Electronic Federal Tax Payment System (EFTPS)
Check or money order (mail with Form 1040-V)
Credit or debit card (note: processing fees apply)

These payments can be designated as extension payments to be applied to your final return.

Final Thoughts

April 15 is more than just the deadline to file Form 1040. It’s a critical day for paying taxes, making retirement contributions, and staying compliant with the IRS.

Filing an extension can buy you time, but it won’t stop the clock on your tax bill. If you’re still gathering documents or working with your accountant, be sure to file Form 4868 or 7004 and make a payment to avoid interest and penalties.