Quick Answer: Yes. For most calendar-year taxpayers, Thursday, October 15, 2026 is the final deadline to file an extended 2025 Form 1040 or Form 1120. The IRS generally does not grant more time after that date. An extension gives you more time to file, not more time to pay, so any balance due has been collecting interest since April 15.
If you filed a tax extension in the spring, the calendar has caught up with you. The fall deadline is just a few weeks away. Whether you’re a grower waiting on year-end harvest numbers, a business owner in the trades, or an individual with a more complicated return, here’s what to know before October 15 arrives.
Who has to file by October 15?
The October 15 date applies to two main groups. Individuals who filed Form 4868 owe an extended Form 1040 by this date. C corporations on extension owe an extended Form 1120 the same day.
Other entity types run on a different calendar. Extended S corporation and partnership returns were due September 15, and extended trust and estate returns were due September 30. This matters for a lot of Central Valley operations structured as family farming partnerships or S-corps — if you own a pass-through business, your K-1s should already be in hand, since they feed directly into your personal return.
What happens if you miss the October 15 deadline?
Penalties start stacking up right away. The IRS charges a failure-to-file penalty of 5 percent of the unpaid tax for each month or part of a month the return is late, up to 25 percent. A failure-to-pay penalty of 0.5 percent per month also applies, and interest compounds daily on any unpaid balance.
If you cannot pay in full, file anyway. Filing on time and paying what you can costs far less than not filing at all.
Does California use the same October 15 deadline?
In most cases, yes. California generally gives individuals an automatic extension to October 15, but like the federal extension, it covers filing only. Payment was still due in April. State rules for corporations and pass-through entities can differ, so confirm the dates that apply to your entity type.
What if you cannot finish your return by October 15?
It happens, especially when a K-1 is still missing or a business return is complicated — and with harvest wrapping up across the Valley this time of year, business owners are often pulled in a dozen directions at once. Do not simply skip the deadline. Talk with your CPA right away about filing a return based on the best information available. You can amend later if a late form changes your numbers.
A return filed on time with an estimate is almost always better than a perfect return filed late. The penalty clock stops when you file, and an amended return costs far less than months of added penalties.
What should you gather before you file?
Missing paperwork is the number one reason extended returns slip past the deadline. Pull these together now:
- All W-2s, 1099s, and K-1s, including any corrected forms
- Brokerage and crypto statements
- Business income and expense reports reconciled to your bank accounts
- Records of 2025 estimated tax payments
- Documentation for large purchases such as equipment or vehicles
- Mortgage, property tax, and charitable giving records
Are there new deductions worth claiming on a 2025 return?
Yes. Tax law changes passed in 2025 apply to returns for that year. Depending on your situation, you may qualify for a higher SALT deduction cap of $40,000, deductions for qualified tips and overtime pay, or an added deduction for taxpayers age 65 and older. In a region where overtime is common across harvest season, healthcare, and the trades, these deductions may matter to a lot of Central Valley households.
Each one has income limits and rules. Have a CPA review your return before you file, not after.
Need help finishing your extended return? Contact DDC today. We will help you file accurately and on time.
Frequently Asked Questions
Can I get another extension after October 15?
Generally, no. The IRS limits filing extensions to six months for most taxpayers. If time is tight, file the best return you can and amend it later if needed.
What happens if I file my extended return after October 15?
Penalties and interest apply to any unpaid tax. If you are owed a refund, there is generally no failure-to-file penalty, but do not wait. Refunds are lost if not claimed within three years of the original due date.
How do I pay a balance due with my extended return?
You can pay through IRS Direct Pay, EFTPS, your IRS online account, or by card. If you cannot pay in full, the IRS offers payment plans. Paying something now reduces the penalties and interest that build on the rest.
Does e-filing on October 15 count as on time?
An e-filed return is generally timely if it is transmitted by the deadline. Filing a day or two early gives you room to fix a rejection without missing the date.
Do I have to file if I owe nothing or expect a refund?
You still need to file if you are required to, and you should file to claim any refund. There is generally no failure-to-file penalty when no tax is owed, but a refund cannot be collected forever, so do not put it off.