Background

Starting a business means more than sales and invoices—the IRS expects timely tax reporting from day one. Owners often feel anxious about the first return because the required form and deadline vary by business type and tax year. Getting it right protects you from penalties, interest, and audit attention.

How it works (quick overview)

  • Choose the correct return for your structure: sole proprietors report business activity on Schedule C (attached to your individual Form 1040); partnerships file Form 1065 and issue Schedule K‑1s; S corps use Form 1120‑S; C corps use Form 1120. (See IRS guidance: https://www.irs.gov/businesses/small-businesses-self-employed)
  • Calendar‑year filers generally follow the standard due dates below; fiscal‑year filers use deadlines tied to their fiscal year end.
  • Many businesses must make quarterly estimated tax payments during the year (Form 1040‑ES for individuals/sole proprietors, corporate estimated payments per IRS instructions).

Common forms and typical deadlines (calendar‑year filers)

Business type Return form Typical due date Common extension form
Sole proprietor (single‑member LLC reporting on owner’s return) Schedule C with Form 1040 April 15 (Tax Day) Form 4868 (individual extension to Oct 15)
Partnership Form 1065 March 15 Form 7004 (automatic 6‑month extension to Sept 15)
S corporation Form 1120‑S March 15 Form 7004 (automatic extension)
C corporation (calendar year) Form 1120 April 15 Form 7004 (automatic extension to Oct 15)

Notes and important details

  • Estimated tax payments: If you expect to owe tax of $1,000 or more after withholding and credits, make quarterly estimated payments to avoid penalties. Sole proprietors use Form 1040‑ES; corporations follow IRS corporate estimated rules. (See IRS estimated tax guidance: https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes)
  • Self‑employment threshold: If your net earnings from self‑employment are $400 or more, you generally must file and pay self‑employment tax (Schedule SE). (See IRS Self‑Employed Individuals Tax Center.)
  • Extensions are for filing time only. An extension does not extend the time to pay taxes owed—taxes must be paid by the original due date to avoid interest and penalties.
  • State and local returns: Most states have separate filing rules and deadlines; check your state’s revenue department.

Real‑world context

In my practice, first‑time filers often miss estimated payments or mix up partnership and individual deadlines. One consulting client who filed his partnership return late paid penalties and interest. Conversely, a sole proprietor who kept quarterly records and paid estimates avoided surprises at tax time and reduced penalties.

Who must file

Almost every active business must file a return of some kind. Requirements depend on structure, gross receipts and net income. For example, a sole proprietor with net self‑employment earnings of $400 or more must file. Partnerships and corporations generally must file regardless of income level.

Practical tips to reduce risk

  1. Keep organized records year‑round—income, receipts, mileage logs and bank statements. See our guide on best practices for tax recordkeeping for small businesses: “Best Practices for Small Business Tax Recordkeeping” (https://finhelp.io/glossary/best-practices-for-small-business-tax-recordkeeping/).
  2. Build a compliance calendar. Use our short guide to building a small‑business tax calendar to track due dates and estimated payment deadlines: “Practical Steps to Build a Small-Business Tax Compliance Calendar” (https://finhelp.io/glossary/practical-steps-to-build-a-small-business-tax-compliance-calendar/).
  3. Confirm entity classification early. If you’re deciding between Schedule C, S‑Corp or partnership treatment, review our comparison: “Choosing the Correct Business Tax Form: Schedule C vs S‑Corp vs Partnership” (https://finhelp.io/glossary/choosing-the-correct-business-tax-form-schedule-c-vs-s-corp-vs-partnership/).
  4. Consider professional help for your first filing—CPAs or enrolled agents can reduce missed deductions and filing errors.

Common mistakes to avoid

  • Using the wrong form for your entity type.
  • Forgetting to issue or keep Schedule K‑1s for partners/shareholders.
  • Missing quarterly estimated tax payments.
  • Treating an extension as extra time to pay.

Short FAQ (brief answers)

  • When is my first business tax return due? For most calendar‑year sole proprietors and C corps it’s April 15; for partnerships and S corps it’s March 15. Check fiscal‑year filers and state rules for differences.
  • Can I extend the deadline? Yes. Individuals (including Schedule C filers) can file Form 4868; partnerships and corporations can file Form 7004. Extensions grant filing time, not payment time.

Professional disclaimer

This article is for educational purposes and does not replace personalized tax advice. For decisions about entity choice, estimated taxes or complex situations, consult a CPA, tax attorney, or enrolled agent.

Authoritative sources

Internal resources