09/14/2026
I know that little stomach-drop feeling when a tax deadline shows up on the calendar, even when you've done nothing wrong. It's such a common feeling that I named this post after it. Here's what's actually due September 15th, so at least the dread has a shape:
→ Individuals: third installment of your 2026 estimated taxes
→ Partnerships: extended Form 1065, plus K-1s/K-3s if applicable
→ S Corporations: extended Form 1120-S, plus K-1s/K-3s if applicable
→ Corporations: third installment of your 2026 estimated taxes
Nobody escapes September without at least one deadline landing on their desk. If any of this applies to you and you're not sure where things stand, reach out — that's exactly what I'm here for.