NC Business Owners: What's Due October 15 If You Extended
Quick Summary: If you filed a tax extension on your 2025 return, October 15, 2026, is your real deadline, but only for certain entity types. This guide covers who's affected (1040 filers with Schedule C, and 1120 C-corporations), what happens if you miss it, and why some entity types are already past their deadline. Written for business owners and self-employed filers who extended in April and need a straight answer on what's next. Book a free consultation if you're still looking for help before the 15th.
Back in April, "extension" felt like relief. Six more months to get your books straight, gather documents, and file without the tax-season crunch. Now it's the beginning of October, and that six-month runway has almost run out; and if you're a North Carolina business owner, this is the deadline our Monroe-based team spends every fall making sure clients don't miss. But there's one important distinction: a tax extension only gives you more time to file your return. It does not extend the deadline for paying any taxes you owe.
Certum Solutions has spent 15+ years as a full-service accounting firm, and a QuickBooks Elite Partner since 2012, helping business owners across North Carolina and the Charlotte metro navigate exactly this moment; the second, quieter deadline that catches people off guard every fall. Our team works through file reviews and spot checks all year, so nothing falls through the cracks when a real deadline hits.
This guide is written for North Carolina small business owners and self-employed filers (and applicable nationwide) who extended their 2025 return and need to know exactly what's due, when, and what happens if they run out of time.
What's Actually Due on October 15, 2026
Not every extended return has the same deadline. If you extended, October 15 applies to you if you file:
Form 1040 with Schedule C - sole proprietors and single-member LLCs reporting business income on their personal return
Form 1120 - C-corporations
October 15 also applies to individual 1040 filers without business income, but for business owners, those are the two that matter. If you're outside those categories
If You File an S-Corp (1120S) or Partnership (1065) Return, Your Deadline Already Passed
S-Corp and partnership extensions were due September 15, 2026, a full month before the individual and C-Corp deadline. If you're reading this and realizing you missed it, you're not alone, and it's fixable, but it needs to be handled carefully.
For business owners still looking for help, there’s an important note about availability: Certum Solutions is not accepting new 1120S or 1065 prep engagements for this filing cycle. Our team is focused on the clients already in our pipeline for the October 15 deadline, and we don't take on new late-entity work we can't do justice to.
If you're already past this deadline and need help anyway, knowing it will be filed late, reach out; we'll tell you honestly whether we can help or point you somewhere that can.
What Happens If You Miss October 15
For 1040 and 1120 filers, missing October 15 means:
Failure-to-file penalties resume (typically 5% of unpaid tax per month, up to 25%)
Failure-to-pay penalties continue accruing if tax was owed and not paid by the original due date. The IRS charges a minimum failure-to-file penalty on returns more than 60 days late.
Interest compounds on any unpaid balance
The IRS has no further automatic extension, after this, you're filing late
The good news: none of this is a reason to panic or avoid filing. It's a reason to file now.
What We're Doing Right Now (and Why It Matters to You)
Our tax team's current focus, in order:
Finishing October 15 extension filings for 1040 Schedule C and 1120 clients
File reviews - buttoning up every 2025 tax file before year-end, so nothing carries forward incomplete
Spot checks on active tax clients between now and December
December organizers go out to this year's clients, kicking off prep for the 2026 tax year
If you're a new prospective client with a 1040 Schedule C or 1120 need before the 15th, this is the moment to reach out; our team still has room to help you file on time. If your need is S-Corp or partnership related, this cycle is closed, but next year's organizer season is coming, and we have the opportunity to build a real relationship starting in December than rush a return in October.
How to Get Ahead of Next Year (Instead of Repeating This)
If this deadline scramble felt familiar, the fix isn't a better extension — it's better bookkeeping and CFO-level visibility throughout the year, so tax season is a formality instead of a fire drill. That's the same reason our ongoing accounting services and fractional CFO support exist: to make sure the numbers are clean well before any deadline shows up.
FAQ
What is the deadline for extended 2025 tax returns?
October 15, 2026, for 1040 returns (including Schedule C filers) and 1120 C-corporation returns.
Is the S-Corp and partnership extension deadline the same as the individual deadline?
No. S-Corp (1120S) and partnership (1065) extensions were due September 15, 2026, one month earlier than the individual and C-Corp deadline.
Is Certum Solutions taking new S-Corp or partnership tax clients right now?
Not for this filing cycle. That extended deadline has already passed, and we're focused on our current clients' October 15 filings. If you already know your return will be filed late, contact us anyway; we'll give you a straight answer on whether we can help.
What happens after October 15 for Certum Solutions clients?
Our team shifts into file review mode; buttoning up this year's tax files, doing spot checks on active tax clients, and preparing to send organizers to clients in December for the next tax season.
What if I miss the October 15 deadline entirely?
You'll want to file as soon as possible regardless. Failure-to-file and failure-to-pay penalties, plus interest, continue to accrue the longer a balance-due return goes unfiled. The IRS charges a minimum failure-to-file penalty on returns more than 60 days late.
Does Certum Solutions work with businesses outside North Carolina?
Yes — we serve clients nationwide, but we're based in Monroe, NC, and North Carolina businesses are our home base and where we have the deepest local expertise.
Why Work with a North Carolina-Based Tax Team
When your filing deadline is this close, working with a team that's local matters. Certum Solutions is based in Monroe, NC, with senior accountant oversight on every file and a team that already knows the state-specific pieces; from NC franchise and corporate income tax nuances to how local business structures typically file. We do take on clients nationwide, but North Carolina businesses are where we're rooted, and it shows in how quickly we can turn around a file that's come down to the wire.
