What are the tax deadlines for small businesses in the US?
Key US small business tax deadlines include: March 15 (S-Corp Form 1120-S and partnership Form 1065), April 15 (individual/sole proprietor Form 1040), January 31 (W-2 and 1099-NEC), and quarterly payroll returns (Form 941) due in April, July, October, and January.
Detailed Explanation
Staying on top of US small business tax deadlines requires managing multiple overlapping calendars for income tax returns, payroll tax filings, estimated payments, and information returns. Missing a deadline triggers automatic penalties, so a clear annual tax calendar is essential.
Annual income tax return deadlines
S-Corporation (Form 1120-S): Due March 15 (calendar year). Extension: September 15 (file Form 7004 by March 15). Note: S-Corp extensions are 6 months.
Partnership (Form 1065): Due March 15 (calendar year). Extension: September 15 (file Form 7004 by March 15). Partnerships issue Schedule K-1 to partners, who need this before filing their individual returns.
C-Corporation (Form 1120): Due April 15 (calendar year). Extension: October 15 (file Form 7004 by April 15).
Sole proprietor/Single-member LLC (Schedule C on Form 1040): Due April 15. Extension: October 15 (file Form 4868 by April 15). Note: extension gives more time to file but NOT more time to pay — estimated tax must be paid by April 15 to avoid underpayment penalties.
Multi-member LLC (treated as partnership): Same as partnership — Form 1065 due March 15, K-1s to members.
Quarterly estimated tax payment deadlines (2025) - Q1 2025 (January-March): April 15, 2025 - Q2 2025 (April-May): June 16, 2025 - Q3 2025 (June-August): September 15, 2025 - Q4 2025 (September-December): January 15, 2026
Quarterly payroll tax deadlines
Form 941 (Employer's Quarterly Federal Tax Return) is due quarterly: - Q1 (January-March): due April 30 - Q2 (April-June): due July 31 - Q3 (July-September): due October 31 - Q4 (October-December): due January 31
Federal tax deposits (EFTPS): most small employers deposit monthly (by the 15th of the following month) or semi-weekly depending on the deposit schedule.
Annual information returns
Form W-2 (employee wages): January 31 to employees; January 31 to Social Security Administration (SSA). Employers with 10 or more W-2s must file electronically.
Form 1099-NEC (contractor payments): January 31 to recipients and the IRS. Required for each contractor paid $600 or more during the year.
Form 1099-MISC: January 31 to recipients; January 31 to IRS (electronic), February 28 (paper). Used for rents, prizes, healthcare payments, and other miscellaneous income.
Form W-3 (W-2 transmittal): January 31 to SSA (together with W-2 Copy A).
Other key deadlines
FUTA (Federal Unemployment Tax Act): Annual Form 940 due January 31. Deposits due quarterly if FUTA liability exceeds $500.
Form 1096 (1099 transmittal): February 28 (paper); March 31 (electronic) — if filing paper 1099s.
FinCEN Beneficial Ownership Information (BOI) Report (2024): New in 2024 under the Corporate Transparency Act — most LLCs and corporations formed before January 1, 2024 must file BOI reports by January 1, 2025. Companies formed in 2024 have 90 days. This is a FinCEN filing, not an IRS filing, but affects nearly all small businesses.
Extension rules
Filing an extension gives more time to file the return, not to pay the tax. If you owe tax, you must pay an estimate by the original due date. If you underpay, interest accrues from the original deadline. Most states follow federal extension dates, but some have separate state extension procedures.
State deadlines
State income tax deadlines generally mirror federal deadlines, but not always. States may have additional filings (annual reports, franchise tax returns, business privilege taxes). Check your specific state's Department of Revenue or Secretary of State website for state-specific deadlines.
Source: IRS Small Business Tax Calendar
Real-World Examples
S-Corp owner's March deadline crunch
An S-Corp owner needs to file Form 1120-S by March 15. This requires finalising bookkeeping for the prior year, calculating reasonable compensation, reconciling distributions, and preparing Schedule K-1 for herself. If the return will not be ready, she files Form 7004 for an automatic 6-month extension to September 15 — but pays any estimated S-Corp-level tax (like built-in gains tax if applicable) by March 15.
Contractor payments and 1099-NEC rush
A sole proprietor paid three freelancers $800, $2,500, and $6,000 during the year. By January 31, she must issue 1099-NEC to each (all received $600 or more) and file copies with the IRS. Missing the January 31 deadline costs $60-$310 per form. Using 1099 filing software, she completes all three filings on January 28, within the deadline.
Common Mistakes to Avoid
- Confusing the payment deadline with the filing deadline when an extension is filed — extension to October gives more time to file, but any unpaid tax still accrues interest from April 15.
- Missing the W-2 and 1099-NEC January 31 deadline because it feels like the tax season is just starting — these are hard January 31 deadlines with per-form penalties.
- Forgetting state tax deadlines, which may differ from federal deadlines — some states require additional filings or have earlier deadlines for specific business types.
- Not filing the FinCEN Beneficial Ownership Information (BOI) Report required by the Corporate Transparency Act — this new 2024 requirement applies to most LLCs and corporations with penalties of $500/day for non-filing.
Frequently Asked Questions
Why does the S-Corp return deadline (March 15) come before the individual return deadline (April 15)?
S-Corp Form 1120-S is due March 15 so that shareholders receive their Schedule K-1s in time to include S-Corp income on their individual Form 1040 by April 15. Partners in partnerships have the same issue — the partnership files Form 1065 by March 15 and issues K-1s. If the pass-through entity extends its return, shareholders/partners may also need to extend their individual returns.
What are the penalties for late filing of Form 1120-S?
The penalty for late filing Form 1120-S is $235 per shareholder per month (or part of a month), up to 12 months. For a single-shareholder S-Corp, the maximum penalty is $2,820. This penalty applies even if there is no tax due at the S-Corp level (S-Corps are pass-throughs with no entity-level tax, but the filing penalty applies separately).
What is the penalty for filing 1099-NEC late?
Penalties for late 1099-NEC filing increase with the degree of lateness. If filed within 30 days of January 31: $60 per form. If filed by August 1: $120 per form. If filed after August 1 or not filed: $310 per form (2024 rates). Intentional disregard carries a penalty of $630 per form with no cap. Maximum annual penalty for small businesses: $588,500.
What is the BOI report and who must file it?
The Beneficial Ownership Information (BOI) Report is a new FinCEN filing required by the Corporate Transparency Act for most LLCs and corporations. It discloses beneficial owners (people who own 25% or more or exercise substantial control) and company applicants. Companies formed before January 1, 2024 had until January 1, 2025. Companies formed in 2024 have 90 days from formation. Penalties: $500/day civil plus $10,000 criminal. Certain large companies, regulated entities, and inactive companies are exempt.
Practical Tips
- Build your annual tax calendar in a project management tool at the start of each year, with reminders set 2 weeks before each deadline — the combination of quarterly payroll, estimated taxes, and annual returns creates a busy and easy-to-miss schedule.
- Issue 1099-NEC forms in mid-January rather than waiting for the January 31 deadline — contractor payment data is available immediately after year end and early filing prevents last-minute errors.
- If you use an S-Corp, discuss extending the Form 1120-S with your accountant before March 15 each year — an extension to September 15 gives far more time for accurate bookkeeping without penalty.
- Keep a copy of every tax filing confirmation (acceptance notice from IRS e-file, payment confirmation from EFTPS) in a dedicated tax filing folder — proof of timely filing protects you if the IRS claims a return was not received.
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