If you’re a business owner, your annual calendar should include tax deadlines. This post covers common tax deadlines that you should be remembering through the year as a small business owner or nonprofit executive.

Annual Income Tax Deadlines
The most important of the deadlines is of course the annual income tax return that all US businesses must file.
Pass-through organizations like S-Corps and Partnerships (many of whom are LLCs in their state) are due two months and 15 days after their fiscal year ends. For most calendar year filers, that means:
- The S Corp Form 1190S is due on March 15
- The Partnership Form 1065 is due on March 15
Sole proprietorships (unincorporated businesses) are another pass-through type of business, and they get another month to finish.
- The Schedule C on Form 1040 is due on April 15, the standard tax due date
Nonprofits and other Charitable Organizations have yet another month. Their taxes are due four months and fifteen days after their fiscal year ends. Here’s a due date schedule for all fiscal year-ends.
- Form 990 is due on May 15 for calendar-year businesses.
This list does not include state corporate income tax deadlines, which are often similar to federal due dates, but not always.
Estimated Tax Due Dates
The IRS wants you to pay tax as you earn income, not just at the end of the year. That means either regular withholding from unemployment or it means paying estimated taxes on Form 1040-ES. If you expect to pay more than $1000 at tax time, or you owed tax a previous year, you’re supposed to make estimated tax payments during the year. If you have withholding you can increase that, alternatively. There are fines and penalties for not paying estimated tax during the year. Use the worksheet in Form 1040-ES to figure out your estimated tax.
You don’t have to pay estimated tax if you meet all three of these criteria: (a) no tax liability for the prior year, (b) you were a US citizen or resident the whole year and (c) your prior tax year covered a 12-month period.
Estimated taxes are divided into four payment periods, or quarters. To pay them, look at the options under “When To Pay Estimated Taxes.” The four quarters are as follows, except when the due dates fall on a weekend or legal holiday, in which case the payments are due the next business day.
- January 1 – March 31: Due April 15
- April 1 – May 31: Due June 15
- June 1 – August 31: Due September 15
- September 1 – December 31: Due January 15 of the following year
States also require estimated taxes, so please do check with your state’s department of revenue for estimated tax rules and deadlines for your particular situation.
Payroll Taxes
Wage reporting for businesses with employees is a lot of work, but really important. Here is what needs to be filed for all employee, contractor and other payments made:
- The IRS wants employers to report wages paid, income tax withholding, social security and Medicare tax. Specific forms and due dates are below.
- The IRS also want to receive all the employment taxes on a deadline. Payroll due dates are many and are either monthly or biweekly. The IRS Tax Calendar has a list of all those payroll tax deposit dates.
- Form 940 is for FUTA (unemployment) and must be filed annually by January 31.
- Form 941 is the quarterly report of wages and withholding. It must be filed by the end of the month that follows the end of the quarter. For example, April 30 is the deadline for the January 1 to March 31 quarter.
- Forms W-2 and W-3 are the annual statements of wages. A Form W-2 must be given to employees by January 31 of the following year reporting their cumulative wages. Form W-3 is the summary form of all employee wages for reporting to the IRS.
- Form 1099-NEC must be provided to contractors and other payment recipients by January 31 of the following year for reporting cumulative non-employee payments.
A full list of all wage-related forms and taxes that must be filed or paid is here, including alternative forms, agricultural employee forms and others. This does not include state-specific withholding, so do check with your individual state department of revenue for additional withholding due dates and regulations!