Resources
Small Business Tax Deadlines & IRS Resources
Key dates for the 2026 tax year, plus links to the IRS publications every small business owner should have bookmarked. Deadlines shift when they fall on weekends or holidays — dates below reflect the adjusted due dates.
Updated for the 2026 tax year. Always verify current-year dates at irs.gov or contact us before filing.
2026 Quarterly Estimated Tax Deadlines
If you're self-employed, a sole proprietor, or an owner of an S-Corp or partnership, you generally need to pay estimated taxes four times a year. Missing these deadlines triggers an underpayment penalty — even if you pay in full by April.
| Quarter | Income Period | Due Date |
|---|---|---|
| Q1 2026 | Jan 1 – Mar 31 | April 15, 2026 |
| Q2 2026 | Apr 1 – May 31 | June 16, 2026 |
| Q3 2026 | Jun 1 – Aug 31 | September 15, 2026 |
| Q4 2026 | Sep 1 – Dec 31 | January 15, 2027 |
Form 1040-ES is used for individual estimated payments. Corporations use Form 1120-W.
2026 Tax Year Annual Filing Deadlines
These are the deadlines for filing returns and information forms for income earned in the 2026 calendar year. Most fall in early 2027.
February 2, 2027
W-2s & 1099-NECs due
Send W-2s to employees and 1099-NECs to contractors. January 31 falls on Saturday; deadline shifts to Monday.
March 2, 2027
Paper information returns to IRS
Deadline to file paper 1099s (MISC, INT, DIV, etc.) with the IRS. Electronic filers get until March 31.
March 16, 2027
S-Corporation & Partnership returns
Form 1120-S (S-Corp) and Form 1065 (Partnership) are due. March 15 falls on Sunday; deadline shifts to Monday.
March 31, 2027
Electronic 1099s to IRS
If you file 1099s electronically, the IRS deadline is March 31 — one month after the paper deadline.
April 15, 2027
Individual & C-Corporation returns
Form 1040 (individual/sole proprietor/single-member LLC) and Form 1120 (C-Corp) returns are due. Also the deadline to request an automatic extension.
September 15, 2027
Extended S-Corp & Partnership returns
Final deadline for S-Corps and Partnerships that filed for an extension in March.
October 15, 2027
Extended individual returns
Final deadline for individuals who requested an extension in April. Note: an extension gives more time to file, not more time to pay.
Keep in mind
Extensions give you more time to file — not more time to pay.
Filing an extension moves your return deadline, but any taxes owed are still due by the original April 15 date. If you file an extension without paying what you owe, you'll face interest and late-payment penalties. A tax planning conversation before April 15 is how you avoid that surprise.
Talk through your situation →Essential IRS Publications for Small Businesses
IRS publications are free, authoritative, and surprisingly readable. These are the ones most relevant to small business owners in Washington state.
Tax Guide for Small Business
The primary IRS guide for sole proprietors and single-member LLCs. Covers income, deductions, accounting methods, and recordkeeping.
irs.gov ↗
Tax Withholding and Estimated Tax
How to calculate and pay quarterly estimated taxes. Essential reading if you're self-employed or have income that isn't subject to withholding.
irs.gov ↗
Business Expenses
Detailed guidance on what business expenses are deductible — home office, vehicle, meals, interest, insurance, and more.
irs.gov ↗
How to Depreciate Property
Covers Section 179 expensing, bonus depreciation, MACRS depreciation schedules, and listed property rules for vehicles and equipment.
irs.gov ↗
Employer's Tax Guide (Circular E)
The complete employer guide to payroll taxes — withholding tables, deposit schedules, W-2 preparation, and employment tax returns.
irs.gov ↗
Starting a Business and Keeping Records
What records to keep, how long to keep them, and how to set up a basic recordkeeping system for a new business.
irs.gov ↗
Independent Contractor or Employee
A concise explanation of how the IRS distinguishes employees from independent contractors — critical for avoiding misclassification penalties.
irs.gov ↗
Business Use of Your Home
How to calculate the home office deduction using both the simplified method ($5/sq ft) and the actual expense method.
irs.gov ↗
Other Useful Resources
Washington State
No state income tax — but B&O tax applies.
Washington has no personal income tax, which simplifies things for many business owners. However, Washington's Business & Occupation (B&O) tax applies to gross receipts — regardless of whether your business is profitable. B&O tax is filed with the Washington State Department of Revenue on a monthly, quarterly, or annual basis depending on your revenue level. If you also collect sales tax, those filings run on the same schedule. These obligations are separate from your federal tax filings and carry their own deadlines.
Free consultation
Deadlines are easier when someone's watching them for you.
Green Consulting works with small businesses in Puyallup, South Hill, Tacoma, and across Pierce County. We track your deadlines, calculate your estimated payments, and make sure nothing gets missed.