September 2026: The Small Business Owner’s HR, Benefits, Payroll, and Tax Compliance Deadlines

As the last month of Q3 and the unofficial start of holiday business planning, September is a notoriously busy month. Here are all the dates you need to keep track of for payroll, HR, benefits, and taxes. 

Important holidays

September 7, 2026

Labor Day

Maybe you’re giving employees the day off or running promos for Labor Day. Make sure you’re prepared either way. 

September 11, 2026

National Day of Service and Remembrance 

The National Day of Service and Remembrance honors the civilians and first responders who lost their lives on September 11, 2001. It’s not an official federal holiday, but lots of businesses honor the day by hanging workplace signage or participating in community events. 

Tax and payroll compliance deadlines

Payroll tax deposits (for semi-weekly depositors)

All employers are responsible for filing Forms 940 and 941 and depositing payroll taxes throughout the year. (Find more info on federal payroll deposits here.)

If you report more than $50,000 in payroll taxes during the lookback period of July 1, 2024, to June 30, 2025, you’re a semi-weekly depositor, so this is your schedule:

Make sure that if you accumulate $100,000 or more in tax liability on a single day, you deposit the amount by the following business day, regardless of your usual deposit schedule. 

A note on local payroll taxes: Your local and state tax agencies might have different payroll deposit schedules, so make sure you know the deadlines you’re responsible for meeting.  

September 10, 2026

Employee tip reporting deadline for August 

If your employees earn tips, they need to report tips of $20 or more that they earned in August. Brush up on tip withholding and reporting requirements here. 

September 15, 2026

Payroll tax deposits for monthly depositors

If you’re on the monthly schedule for payroll, your tax deposit for August payrolls is due on September 15. 

Estimated tax payment for Q3 due 

If you make quarterly estimated tax payments, your third payment of the year is due September 15. You have to make quarterly estimated tax payments if you fall into one of the following categories:

• C corporations

• S corporation shareholders

• Partners

• Sole proprietors 

• Independent contractors

• Freelancers 

• Gig workers

You can pay online, over the phone, or via mail using Form 1040-ES. For more information on estimated taxes, review Publication 505.

Form 8813 quarterly payment voucher due for partnerships 

If you’re a partnership, you need to file Form 8813 by September 15 and pay any tax due. You can file the form at this address:

Internal Revenue Service Center
P.O. Box 409101
Ogden, UT 84409

For more information on Form 8813, see the IRS instructions here. 

Form 1120-S extended filing deadlines for S-corps

If you own an S corporation (or if your LLC is taxed as an S corp), you have to use Form 1120-S to report your income, losses, and dividends as a shareholder of the company. This form was due in March, but if you requested a six-month extension via Form 7004, your deadline is now September 15. 

You also have to pay any tax, interest, or penalties at this time, and give each partner a copy of their final Schedule K-1 or Schedule K-3 (Form 1120-S). 

Form 1065 extended filing deadlines for partnerships

If you own a partnership (or an LLC set up as a partnership) and didn’t file Form 1065 back in March because you requested a six-month extension, your new deadline is September 15. Keep in mind that each partner is responsible for paying their share of income from the business on their personal tax returns (Form 1040).

Make sure you also give each partner a copy of their final Schedule K-1 or Schedule K-3 (Form 1065), if applicable. 

Estimated tax payment due for Q3 for tax-exempt organizations

When you own a tax-exempt organization like a nonprofit, you need to pay estimated tax on unrelated business income by September 15. Keep in mind that this is only if you expect your tax liability to be more than $500. 

You can use Form 990-W to calculate the amount of estimated tax required. 

Form 1042 extended filing deadline 

If you withhold taxes for international employees, you’re required to submit Form 1042 on an annual basis to report those withholdings. If you requested a six-month filing extension, the form is due September 15. 

September 30, 2026

End of Q3 for companies following the calendar year

If you operate on a calendar year, the third quarter ends at the end of the month on September 30. 

Form 2290 filing deadline for vehicles first used in August 

If your business’s newly registered heavy highway motor vehicle was first used in August, you have to file Form 2290 by September 30. 

Form 730 filing deadline for wagers in August

If you’re in the business of accepting wagers and you accepted some during August, you have to file Form 730 by September 30. Learn more about Form 730 here.

HR compliance deadlines

September 15, 2026

Deadline to make retirement plan employer contributions for partnerships and S corporations

Partnerships and S corps that filed a corporate tax extension need to make any 2025 employer profit-sharing and matching contributions by September 15.

Minimum funding contributions due for defined benefit plans

If your business has a defined benefit, money purchase, or target benefit plan that follows the calendar year, you have to meet your minimum funding requirement for the 2025 plan year by September 15, eight and a half months after the end of the plan year in question. 

If you have a pension plan that doesn't have a funding shortfall for 2026, your minimum funding deadline for the 2025 plan year is also due. 

Form 5500 due for certain plans

If your business offers pension or welfare benefit plans covered by the Employee Retirement Income Security Act of 1974 (ERISA), you’re required to file Form 5500 with the Employee Benefits Security Administration (EBSA). This form reports information about these plans, including their qualification, financial condition, operation, and investments. 

Although Form 5500 is typically due on July 31, plan sponsors who qualify for an automatic corporate tax extension have until September 15. 

Pension Benefit Guaranty Corporation premiums due

The Pension Benefit Guaranty Corporation (PBGC) collects flat-rate and variable-rate insurance premiums from plan sponsors every year. Your business has to pay a premium for every one of your plan participants in case the pension plans are terminated. 

For single-employer plans that began in 2026, the per participant flat rate is $111; for multiemployer plans that began in 2026, the per participant flat rate is $40. These premiums are due by September 15. You can see the full rate sheet here. 

September 30, 2026

Deadline to furnish the Summary Annual Report for calendar-year plans

A Summary Annual Report (SAR) is a summary of the information you submit in your Form 5500, including the total value of your company’s benefit plan during the previous plan year and other details. 

If you operate on a calendar year, your deadline to give the SAR to your employees is September 30 (within nine months of the end of the plan year). 

If you’ve successfully filed for an extension with Form 5558, your deadline for furnishing SARs to your employees will be December 15.

Remind employees to use their benefits

Your employees only have a few months left to take advantage of employee benefits that expire at the end of the calendar year, like unused paid time off, FSAs, and wellness stipends.