2025 Small Business Tax Calendar: Every Federal Deadline You Need to Know
Missing tax deadlines is the most preventable cause of penalties for small businesses. The IRS charges penalties automatically when returns or payments are late, with no grace period and limited waiver options. The key insight: always file on time, even if you can’t pay. The failure-to-file penalty (5% per month, up to 25%) is ten times higher than the failure-to-pay penalty (0.5% per month, up to 25%). Filing on time with a $0 payment avoids the larger penalty and gives you time to arrange payment. Extension requests (Form 4868 for individuals, Form 7004 for businesses) extend the filing deadline but NOT the payment deadline. Estimated taxes are paid in full on the original due dates regardless of extensions.
2025 tax calendar (federal deadlines, calendar-year businesses):
January:
| Date | Deadline |
|---|---|
| Jan 15 | Q4 2024 estimated tax payment (individuals, if not paying with return) |
| Jan 31 | W-2s to employees (and W-3 + Copy A to SSA) |
| Jan 31 | 1099-NEC to recipients AND to IRS |
| Jan 31 | 1099-MISC to recipients |
| Jan 31 | Form 940 (FUTA annual return) |
| Jan 31 | Q4 2024 Form 941 (quarterly payroll return) |
February / March:
| Date | Deadline |
|---|---|
| Feb 28 | 1099-MISC Copy A to IRS (paper filing) |
| Mar 15 | S-Corp return (Form 1120-S) and K-1s to shareholders |
| Mar 15 | Partnership return (Form 1065) and K-1s to partners |
| Mar 15 | Form 2553 (S-Corp election, effective Jan 1 of current year) |
| Mar 31 | 1099-MISC Copy A to IRS (electronic filing) |
April:
| Date | Deadline |
|---|---|
| Apr 15 | Individual return (Form 1040) including Schedule C |
| Apr 15 | C-Corp return (Form 1120) for calendar-year corporations |
| Apr 15 | Q1 estimated tax payment (individuals and corporations) |
| Apr 15 | SEP IRA contribution (if filing without extension) |
| Apr 15 | Solo 401(k) employer contribution (if filing without extension) |
| Apr 15 | Last day for prior-year IRA contribution ($7,000/$8,000) |
| Apr 30 | Q1 Form 941 (quarterly payroll return) |
June:
| Date | Deadline |
|---|---|
| Jun 15 | Q2 estimated tax payment |
July:
| Date | Deadline |
|---|---|
| Jul 31 | Q2 Form 941 (quarterly payroll return) |
September:
| Date | Deadline |
|---|---|
| Sep 15 | Q3 estimated tax payment |
| Sep 15 | S-Corp return (extended deadline) |
| Sep 15 | Partnership return (extended deadline) |
October:
| Date | Deadline |
|---|---|
| Oct 1 | SIMPLE IRA plan must be established (for current-year contributions) |
| Oct 15 | Individual return (extended deadline) |
| Oct 15 | SEP IRA contribution (with extension) |
| Oct 15 | Solo 401(k) employer contribution (with extension) |
| Oct 15 | C-Corp return (extended deadline) |
| Oct 31 | Q3 Form 941 (quarterly payroll return) |
December:
| Date | Deadline |
|---|---|
| Dec 31 | Solo 401(k) plan must be ESTABLISHED (new plans) |
| Dec 31 | Solo 401(k) employee deferrals must be made |
| Dec 31 | Estimated tax safe harbor review (adjust Q4 payment if needed) |
January (following year):
| Date | Deadline |
|---|---|
| Jan 15 | Q4 estimated tax payment |
| Jan 31 | W-2s and 1099-NECs |
Penalty summary:
| Penalty | Rate | Maximum |
|---|---|---|
| Failure to file | 5% per month | 25% of tax due |
| Failure to pay | 0.5% per month | 25% of tax due |
| Both combined | 5% per month (FTF reduced by FTP) | 47.5% total |
| Late Form 941 | 2-15% of tax due | 25% |
| Late W-2/1099 | $60-$310 per form | Varies by business size |
| Late estimated tax | Interest rate (~7-8%) | No maximum |
What does a small business owner need to do each quarter?
What penalties apply for underpaying estimated taxes?
The IRS charges an underpayment penalty under IRC 6654 when you owe more than $1,000 at filing and your withholding and estimated payments are less than the required annual amount. The penalty is calculated separately for each quarter, so a large payment in Q4 doesn’t fully cure an underpayment from Q1 through Q3. You avoid the penalty entirely if your payments cover at least 90% of the current year’s tax or 100% of last year’s tax (110% if your AGI exceeded $150,000). The penalty rate is the federal short-term rate plus 3 percentage points, compounded daily. If your income varies significantly during the year, the annualized income installment method (Form 2210, Schedule AI) can reduce or eliminate the penalty by matching payments to when income was actually earned.
How do I estimate my tax liability for the first year of business?
In your first year, you have no prior-year tax liability to base the safe harbor on, so you must estimate your current-year income. Start with projected gross revenue, subtract estimated deductible expenses, and apply the self-employment tax rate (15.3% on the first $168,600 of net earnings in 2024, 2.9% above that) plus your expected income tax bracket. A conservative approach is to set aside 25-30% of net profit for each quarterly payment. If your income is uncertain, pay a reasonable estimate for Q1 and adjust in Q2 once you have actual numbers. Overpayments are refunded or applied to next year’s estimated taxes.
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Yarik Yarosh, CPA. "2025 Small Business Tax Calendar: Every Federal Deadline You Need to Know." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-federal-tax-deadline-calendar-quarterly
This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.