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

Quarterly tax deadlines abound in October. It’s important to know exactly what to plan for, so you can automate compliance as much as possible and focus on meeting your final goals for 2026. 

These are the tax, payroll, benefits, and HR deadlines to mark down. 

Significant holidays

National Disability Employment Awareness Month

October is National Disability Employment Awareness Month (NDEAM), and this year’s theme is a continuation of last year’s—Celebrating Value and Talent—in honor of the United States’s 250th anniversary.  

NDEAM is designed to celebrate workers with disabilities, promote inclusivity in workplaces, and give employers practical resources and tools for supporting employees with disabilities. Learn more on the Department of Labor’s website.

October 12, 2026

Indigenous Peoples’ Day (Columbus Day)

Many states and cities observe Indigenous Peoples’ Day to honor the histories and contributions of Indigenous American people. Only a handful of states—Maine, Nebraska, New Mexico, and South Dakota—consider the day a holiday, but many businesses in those places give their employees the day off. 

Check here to see whether your state observes Indigenous Peoples’ Day or recognizes it as an official paid holiday. 

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.  

October 1, 2026

For calendar-year followers, October 1 is the official start of Q4. 

October 13, 2026

Employee tip reporting deadline for September 

If your employees receive tips, they need to report tips they earned (over $20) in September; the deadline is October 13. 

October 15, 2026

Payroll tax deposits for monthly depositors

If you’re on the monthly payroll tax deposit schedule (meaning that you reported less than $50,000 in payroll taxes during the lookback period), your tax deposit for September Social Security, Medicare, and withheld income tax is due on October 15. 

Form 1040 extended filing deadline for sole proprietors and single-member LLCs

If you’re a sole proprietor or single-member LLC and you requested an automatic six-month extension on filing your 2025 tax returns, your deadline to file Form 1040 is October 15. You also need to pay any tax, interest, or penalties due. 

Form 1120 extended filing deadline for corporations

If your C-corporation requested an automatic six-month filing extension, you have to file Form 1120 by October 15. 

You can file your returns by mail or online, but if your business needs to file 10 or more information returns per year (i.e., W-2s, 1099s), you’re required to file your taxes electronically. 

Find Form 1120 e-filing guidelines and general instructions on the IRS website. 

HR compliance deadlines

October 2, 2026

QSEHRA annual notice delivery to plan participants

October is when you can begin disseminating Qualified Small Employer Health Reimbursement Arrangement (QSEHRA) notices to your benefits plan participants. You have to send these notices out 30 to 90 days before the start of the calendar year you’ll be offering the QSEHRA. 

Make sure you send the following notices:

• 401(k) safe harbor match

• Automatic contribution arrangement (ACA)

• Qualified automatic contribution arrangement (QACA)

• Qualified default investment alternative (QDIA) 

RDS application due to CMS

The Retiree Drug Subsidy (RDS) is an application that helps employers support Medicare-eligible retirees in getting better drug coverage. The RDS application is due to the Centers for Medicare and Medicaid Services (CMS) 90 days before the start of the plan year. If your plan year begins on January 1, 2027, your RDS application is due October 2. 

Learn more about the RDS application and how to submit it on the CMS website. 

October 15, 2026

Employer retirement contributions due for certain employers

If you’re a sole proprietor or C corp and received approval for an extended tax filing deadline of October 15, you also have to make any final employer retirement plan contributions for the 2026 tax year by this date.

Medicare Part D Notice of Creditable Coverage due to plan participants

If you have a group health plan and provide prescription drug coverage, you’re required to tell individuals who are eligible for Medicare Part D (and people who are about to become eligible) whether their plan’s coverage is at least as good as Medicare’s—in other words, whether it’s “creditable” or “non-creditable.”

Individuals are eligible for Part D if they meet one of the following criteria:

• Are 65 or more years old

• Are three months away from turning 65 years old

• Have a disability

You have to disclose this information to all eligible individuals electronically or via mail before October 15, so make sure to plan ahead. This ensures your plan participants have the information they need to decide whether they need Medicare prescription coverage ahead of the annual enrollment period, which begins in November.

You can see CMS templates for these notice letters here.

Deadline to correct a minimum coverage requirement or nondiscrimination failure 

If you offer retirement plans, you’re required to test those plans every year to ensure they 1) meet minimum coverage requirements and 2) pass the Actual Deferral Percentage (ADP) and Actual Contribution Percentage (ACP) nondiscrimination tests. 

If you fail to meet the requirements of your plan, you have until October 15 to file a retroactive amendment to correct your mistakes. For complete instructions on how to fix a failed ADP or ACP test, review the IRS’s guide. 

Third quarter minimum funding payment due for certain defined benefit pension plans

If you have a defined benefit pension plan that experienced a funding shortfall in 2025, you have to make your third-quarter minimum funding contribution for the 2026 plan year by October 15 (due 15 days after the end of the quarter). 

Form 5500 due for extended deadline recipients

If you received a filing extension for Form 5500, the annual employee benefit return, whether by filing Form 5558 or Form 7004, your new deadline is October 15. 

QSLOB filing deadline

Qualified separate lines of business (QSLOBs) are different arms of a company that, for IRS purposes, have their own retirement plan contribution and testing rules (rather than being lumped under the same entity-wide compliance umbrella). 

If you need to establish a QSLOB, your deadline to file Form 5310-A with the IRS to give notice is October 15.