What Happens If You Miss the September 15th Tax Deadline? - MABE International Advisors

Sep 08 2025 12:00

Every year, September 15th comes with high stakes for many business owners. If your company filed an extension back in March, this is your new deadline to submit tax returns. But what happens if youre not readyor worse, if you completely miss the date?

Lets break it down.

Who Does the September 15 Deadline Apply To?

The September 15 deadline is specifically for:

  • Partnerships filing Form 1065
  • S Corporations filing Form 1120-S
  • LLCs taxed as a partnership or S corporation

If your business structure falls under these categories and you filed for an extension earlier this year, the IRS expects your return by September 15.

The Consequences of Not Filing on Time

Missing this deadline doesnt just cause stressit can hit your wallet hard. Heres how:

1. Late Filing Penalties

  • Partnerships: $245 per partner, per month, up to 12 months.
  • S Corporations: $245 per shareholder, per month, up to 12 months.

This means if your partnership has four partners and you file three months late, thats $2,940 in penaltiesjust for missing the filing date.

2. Interest on Unpaid Taxes

Even though S corps and partnerships are pass-through entities, penalties still apply if owners personal returns are affected. Interest starts accumulating immediately on any unpaid amounts.

3. Administrative and Legal Headaches

Falling out of compliance with the IRS can affect your companys good standing, create state-level issues, and complicate future financing or investor opportunities.

What To Do If Youre Not Ready to File

If youre staring at the deadline and your books still arent ready, dont panic. You still have options:

  1. File ASAP  Even if incomplete, filing now reduces the total penalty. Remember, the IRS calculates late fees monthly, not daily.
  2. Pay What You Can  Partial payments lower the amount of interest charged.
  3. Request Penalty Abatement  If this is your first late filing or you have a valid reason (illness, natural disaster, etc.), you can request relief.
  4. Get Professional Help  An experienced tax advisor can step in, organize whats missing, and deal directly with the IRS on your behalf. Contact us and we’ll handle this for you.

Dont WaitTake Action Now

The longer you wait, the more penalties add up. Filing even a week late could mean hundreds or thousands of dollars in unnecessary fees.

If youre not sure where to start, let us handle everything for you. Well take the stress off your plate, file accurately, and help you minimize penalties.

 Contact us today to get your filing back on track before it costs your business more than it should.