When is the corporate tax return due?
C-Corp Form 1120: 15th day of the 4th month after fiscal year end (April 15 for calendar-year corps). S-Corp Form 1120-S: March 15. Multi-member LLC partnership Form 1065: March 15. Single-member LLC Schedule C with personal return: April 15.
How the S-Corp election actually saves you money.
If you're researching when is the corporate tax return due, here are the supporting details founders typically want to know:
- The short answer: C-Corp Form 1120: 15th day of the 4th month after fiscal year end (April 15 for calendar-year corps). S-Corp Form 1120-S: March 15. Multi-member LLC partnership Form 1065: March 15.
- What it means for your business: The practical impact varies by entity type, state, and business stage.
- When this matters: Most often relevant at formation, annual compliance cycles, or when planning major changes.
- Where to verify: State Secretary of State websites, IRS publications, FinCEN guidance, and licensed professionals are authoritative sources.
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Start my business Talk to a specialistWhen this matters in practice
The answer above covers the core question. Practical application depends on a few factors most founders should think about:
- Entity type: The right answer can vary depending on whether you're operating as a sole proprietorship, LLC, S-Corp, C-Corp, or nonprofit.
- State of formation: US business law varies significantly state by state. What's true in Delaware may differ in California or Texas.
- Business stage: Pre-revenue, growing, scaling, and exit-ready businesses each face different versions of this question.
- Industry context: Regulated industries (healthcare, legal, financial services, food, alcohol) face additional rules layered on top of the general answer.
Verify specifics against the relevant Secretary of State website, IRS publications, FinCEN guidance, or a licensed professional for advice on your specific situation.
Common mistakes to avoid
Missing deadlines
State and federal deadlines tied to business formation and compliance are strict. Missing them often results in late fees, loss of good standing, or administrative dissolution. File.Business compliance suite tracks every deadline across all 51 jurisdictions automatically.
For most founders, the safest approach is to set up the right systems before you need them rather than scrambling at the deadline. File.Business handles formation, BOI reporting, annual reports, and state-specific compliance from one dashboard with a penalty-free guarantee.