Filing on Extension? What to Do Before the October 15 Deadline

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If you filed for an extension back in April, your extra time is almost up. The extended deadline for 2025 federal individual tax returns is October 15, 2026 — that’s just days away. Whether you’ve been putting it off or your paperwork only recently came together, here’s how to get it done without tripping over the mistakes that cause the most headaches.

What to have ready before you sit down

Last-minute filers usually stall on the same handful of documents. Gather these first and the rest goes much faster:

  • All income documents: W-2s, 1099s (including 1099-NEC for contract work, 1099-INT/DIV for bank and investment income), and any K-1s if you’re in a partnership or S corporation. K-1s are the classic last-minute straggler — if you never received one you were expecting, call the issuer now, not October 14.
  • Records of estimated payments: If you made quarterly estimated payments, have the amounts and dates. People forget these constantly, and the IRS won’t credit what it can’t match.
  • Deduction and credit documentation: Mortgage interest statements, property tax receipts, charitable donation records, childcare expenses, education expenses, and HSA contributions. Texas filers: remember there’s no state income tax return to worry about, but your property taxes and mortgage interest still matter on the federal side.
  • Last year’s return: It gives you (or your preparer) a baseline to compare against and catches things like carryover losses you might otherwise miss.

The mistakes that trigger IRS notices

When people rush, the IRS notices. These are the errors we see most often from last-minute returns:

  1. Mismatched income. The IRS receives copies of your W-2s and 1099s. If what you report doesn’t match what they have, you’ll get a notice — usually months later, with interest attached. Double-check every number against the actual document, not your memory of it.
  2. Wrong bank account numbers. Direct deposit of a refund to a mistyped account is a miserable problem to unwind. Read the routing and account numbers twice.
  3. Unsigned returns. An e-filed return needs your PIN or prior-year AGI to count as signed. A paper return needs an actual signature. Unsigned returns aren’t considered filed — and “I mailed it” doesn’t help if it was never valid.
  4. Forgetting the extension payment. An extension gives you more time to file, not more time to pay. If you owed tax and didn’t pay by April, interest and penalties have been running since then. Paying now still stops the bleeding.

What happens if you miss October 15

Let’s be honest: some people won’t make it. Here’s the reality, without the scare tactics:

  • The failure-to-file penalty is typically 5% of the unpaid tax for each month (or part of a month) the return is late, up to 25%. It starts accruing the day after the deadline.
  • The failure-to-pay penalty is smaller — generally 0.5% per month — plus interest on what you owe.
  • If you’re owed a refund, there’s no penalty for filing late. But you generally have three years to claim it before it becomes the government’s money. Don’t leave it on the table.
  • Can’t pay in full? File anyway. This is the single most important point. The penalty for not filing is roughly ten times the penalty for not paying. Then look into an IRS payment plan (installment agreement) — most taxpayers who owe under a certain threshold can set one up online in minutes.

When to call a pro instead of rushing

Some situations are worth handing off rather than powering through at 11 p.m. on October 14:

  • You have self-employment income, rental property, or a K-1 you don’t fully understand.
  • You received an IRS notice about a prior year and aren’t sure it’s resolved.
  • You owe more than you can pay and need help weighing an installment agreement against other options.
  • You’ve started the return twice and keep getting stuck in the same place — that’s a sign, not a failure.

A preparer who’s done thousands of these can usually spot in twenty minutes what would take you all weekend.

The bottom line

October 15 is a hard deadline, not a suggestion. Get your documents together now, double-check the numbers the IRS already has, file even if you can’t pay in full, and don’t let perfectionism turn into a missed deadline.

This article is general educational information, not tax advice. Everyone’s situation is different — consult a qualified tax professional about yours.

Need a hand before the deadline? My Income Tax Refund Inc. is based in Houston and prepares individual and business tax returns for filers in all 50 states. If your extension return is still sitting unfinished, call us at 888-892-4829 and we’ll help you get it filed right — before October 15.