You Missed the March 16th S-Corp Deadline. Here's What to Do.

Okay, so March 16th came and went. Life happened. Maybe you were slammed with a big project, maybe your previous accountant dropped the ball, maybe you just didn't know this deadline existed.

You're not alone. And more importantly — you're not out of options.

We get calls about this every single tax season. Bay Area business owners who missed the S-Corp deadline (Form 1120-S) or the Partnership return deadline (Form 1065) — and they're scared of what happens next. The good news is that this is almost always fixable. The bad news is that the fix gets more expensive every month you wait.

So let's talk through exactly what's going on, and what you should do right now.

What Was Due on March 16th?

If you run an S-Corporation or a Partnership (including most LLCs taxed as partnerships), March 16th was your federal filing deadline for the 2025 tax year.

These returns — the Form 1120-S and Form 1065 — are what the IRS calls "pass-through" entities. The business income flows directly to you and your partners or shareholders, who then report it on their personal returns. The reason the deadline is earlier than April 15 is so that K-1 forms can go out to everyone in time for them to file.

If you filed Form 7004 by March 16, great — you've got until September 15 to actually file. But if neither the return nor the extension went in, you're in late-filing territory and penalties are already running.

How Bad Are the Penalties?

Let's be real about the numbers.

The IRS charges $255 per partner or shareholder, per month for a late S-Corp or Partnership return — up to 12 months. So if you've got a five-person partnership that's two months late, you're already looking at $2,550 just in federal penalties. Three months late? $3,825.

California's FTB adds on top of that — $18 per person per month, plus a potential $2,000 demand penalty if they send you a formal notice and you still don't file within 60 days.

These aren't hypothetical. They're real. And they're already running. We covered more of this in our article on California business tax penalties if you want the full picture.

The Single Most Important Thing You Can Do Right Now

File the return. Today.

I know that sounds obvious. But the number of people who sit on this waiting to "get everything perfect" is remarkable — and every week they wait, the penalties go up. Get a return filed, even if it's not 100% polished, and then deal with the penalty conversation afterward.

Once it's filed, there are two legitimate ways to get those penalties reduced or eliminated:

First-Time Penalty Abatement is genuinely one of the most underused tools in tax law. If you've had a clean compliance history for the past three years — no missing returns, no prior penalties — you can often get the whole penalty wiped out just by asking. Call the IRS or have your CPA do it. It works more often than people expect.

Reasonable Cause Relief is available if you had a legitimate reason for missing the deadline — a serious illness, a natural disaster, or even bad advice from a prior professional. The IRS actually considers these arguments if they're made correctly.

For smaller partnerships — 10 or fewer individual partners, no special allocations — IRS Rev. Proc. 84-35 provides automatic penalty relief in many cases. But your CPA needs to know to invoke it, because it doesn't happen on its own.

Wait — Did You Also Miss the S-Corp Election Itself?

This is a separate issue that trips up a lot of Bay Area founders. You may have set up an LLC intending it to be taxed as an S-Corp — but never actually filed Form 2553 to make that election official. Or maybe you filed it late.

Here's the relief you need to know about: IRS Revenue Procedure 2013-30.

This allows a late S-Corp election if you intended to be an S-Corp from the start, the only issue is the timing, and you had a reasonable cause for the delay. You attach a statement, write "FILED PURSUANT TO REV. PROC. 2013-30" across the top of Form 2553, and file it with your 1120-S. EY has a really clear breakdown of how S elections go wrong and how to fix them — worth a look.

If that route doesn't apply, the next option is a Private Letter Ruling — which costs $43,700 in IRS filing fees. That tends to motivate people to explore Rev. Proc. 2013-30 more seriously. We help clients think through when S-Corp conversion makes sense all the time — but it only works if the paperwork is actually filed.

Why This Hits Harder in 2026 — Your QBI Deduction Is on the Line

Here's the part that turns a compliance headache into a real financial hit.

The OBBBA (One Big Beautiful Bill Act), signed into law July 4, 2025, made the Section 199A Qualified Business Income (QBI) deduction permanent. Under the new 2026 rules, eligible business owners can deduct up to 20% of qualified business income from their federal taxes. For a Bay Area business owner generating $400,000 in qualified income, that's an $80,000 deduction.

But here's the catch: that deduction only works if your entity is properly classified and your return is filed. Your K-1 has to go out before your partners and shareholders can claim it on their personal returns. No return, no K-1, no deduction.

Barnes Dennig breaks down the OBBBA's QBI changes well if you want more detail. Baker Tilly's full OBBBA analysis is excellent for the bigger picture. And just so you know — California does NOT conform to the QBI deduction. It's a federal-only benefit, which is one of many reasons year-round tax planning with your San Francisco accountant is worth the investment.

Your Quick Action Plan

Here's what to do, in order:

1. File the return immediately — don't wait for the perfect moment

2. Issue K-1s right away — your partners/shareholders may need them to file personal extensions

3. Pay any tax owed — failure-to-pay penalties run separately and interest is accruing

4. Request penalty abatement — once filed, your CPA can go to work on reducing what you owe

5. Get ahead of next year — if you're winging it on deadlines, it's time for a better system

Millancpa has a solid overview of 2026 pass-through tax rules if you want context on the bigger structural picture. And this 2026 California business tax deadline guide from KDA is worth bookmarking so you never end up in this spot again.

Is Your Business Structure Even Right?

One more thing worth saying: a lot of the Bay Area business owners who miss this deadline are in the wrong structure to begin with. They're operating as a sole proprietor or a default LLC when they should be in an S-Corp — with lower self-employment taxes, a proper salary/distribution split, and that QBI deduction flowing through properly.

If you haven't had a real LLC vs. S-Corp analysis done for your California business, there's a real chance you're overpaying. We've also written about what 1099 earners and freelancers miss on deductions — a lot of the same principles apply.

Other great firms doing solid work in this space if you're shopping around: Sensiba has deep California tax roots, Kruze Consulting is excellent for startups, and Withum brings national firm depth to Bay Area businesses.

We Can Help You Fix This Fast

At Asnani CPA, we deal with late filing situations all the time. We know the procedures, we know what the IRS responds to, and we know how to move quickly without making things worse. Our team serves business owners across San Francisco, San Jose, Palo Alto, Santa Clara, and the broader Bay Area.

If March 16th came and went and you're still sitting on an unfiled return — reach out today. The sooner we file, the less this costs you.

Talk to us at Asnani CPA →