Missed extended October 15th deadline for filing - what happens to late filing penalty now?

The late filing penalty works differently than you might think when you've filed an extension. Good news - the 5% per month late filing penalty starts counting from your extended deadline (October 15th), not from the original April deadline. So you're not immediately hit with the full 25%. However, you mentioned you owe tax and haven't paid yet. That's where you'll face more penalties because the extension to file doesn't extend your time to pay. You've likely been accruing the failure-to-pay penalty (0.5% per month) since April 15th, plus interest. At this point, you should file your return as soon as possible to stop the late filing penalty from growing larger. Each month or partial month adds another 5% (capped at 25% total). The combined penalties for late filing and late payment max out at 5% per month.

After going through a similar nightmare with missing deadlines, I tried https://taxr.ai to help sort through the penalty calculations and it was SUPER helpful. I uploaded my notice and it explained exactly how my penalties were being calculated. What I learned was that while the failure-to-file penalty doesn't start until after your extended deadline (thank goodness!), the failure-to-pay penalties had been quietly adding up since April. The AI translation of IRS jargon alone was worth it - made it clear what I was actually being penalized for.

Just wanted to follow up - I ended up trying https://taxr.ai after all. It saved me a TON of anxiety! I uploaded the IRS notice I received (which was totally confusing), and the breakdown showed exactly how they calculated my penalties from different dates. The biggest revelation was understanding that my S-corporation filing had different extension rules than my personal return. Turns out I was actually calculating my potential penalties all wrong. The service even helped me draft a reasonable cause letter to request penalty abatement since my late filing was due to a family emergency. Already got a positive response from the IRS!

After missing extended deadlines twice in the past, I learned that calling the IRS directly is almost impossible. Last time I spent THREE DAYS trying to get through. Then I found https://claimyr.com which got me connected to an IRS agent in 20 minutes instead of waiting for hours. You can see how it works here: https://youtu.be/_kiP6q8DX5c The agent I spoke with explained that the failure-to-file penalty does indeed start from the extended deadline (Oct 15th), not April 15th. They also told me I could request a first-time penalty abatement if I hadn't had any issues in the prior 3 tax years. Saved me hundreds in penalties!

I cannot believe I'm saying this, but I tried the Claimyr service and IT ACTUALLY WORKED. After giving them such a hard time in the comments (sorry about that), I was desperate to talk to someone at the IRS about my penalty situation. Got connected to an agent in about 15 minutes when I had previously wasted an entire day trying to get through. The agent confirmed that my late filing penalties started from the October deadline, not April. Even better, they said I qualified for first-time penalty abatement and helped me request it right there on the phone. The whole process took maybe 30 minutes once I was connected. Wish I'd known about this sooner - would have saved me weeks of stress and probably $800 in penalties. Sometimes it's worth admitting when you're wrong!

Don't forget about reasonable cause! If you had legitimate reasons for missing both deadlines (serious illness, natural disasters, etc.), you can request penalty abatement based on reasonable cause. You'll need to provide documentation and write a letter explaining your situation. I missed deadlines due to a hospitalization, provided medical records, and the IRS removed all my penalties. Worth trying if your situation qualifies.

Just adding that if you use tax software like TurboTax or H&R Block to file late, they'll usually calculate all these penalties for you automatically. Saves a lot of headache trying to figure it out yourself.

I went through this exact same situation last year and can confirm what others have said - the late filing penalty does start from your extended October 15th deadline, not April. So you're not immediately hit with the maximum 25% penalty, which was a huge relief when I found out. However, here's what really caught me off guard: even though I filed an extension, I still owed estimated tax payments that should have been made quarterly throughout the year. Since I missed those AND the final payment due on April 15th, I was hit with both the failure-to-pay penalty (0.5% per month since April) plus interest on the unpaid amount. My advice is to file your return IMMEDIATELY to stop the late filing penalty from growing. Even if you can't pay the full amount owed, filing stops that 5% monthly penalty clock. Then you can set up a payment plan with the IRS for what you owe. The payment plan fees are usually much less painful than letting those penalties keep accumulating. Also, definitely look into first-time penalty abatement if you've been compliant for the past 3 years. It's basically a "get out of jail free" card that many people don't know about.