Don’t Overlook the October 31st Deadline: Q3 Payroll & Sales Tax for California Businesses

For successful business owners across San Diego, Los Angeles, and Orange County, fall is a gauntlet of tax deadlines. Just as the dust settles from the October 15th extended income tax deadline, another critical date immediately demands your attention: October 31st.

If you run a company with employees, or if your business collects sales tax, the end of October marks the deadline for your Q3 payroll and sales tax returns. At Greg Wilson & Associates CPAs, we know that high-net-worth entrepreneurs and business owners don’t have the bandwidth to constantly chase deadlines. You need a proactive tax advisor who manages your compliance while you focus on scaling your enterprise.

Here is what you need to know about the upcoming October 31st business tax deadlines—and why missing them is a costly mistake.

If you have employees on payroll, the IRS requires you to file Form 941 (Employer’s Quarterly Federal Tax Return) by October 31st. This form reconciles the federal income taxes, Social Security taxes, and Medicare taxes you withheld from your employees’ paychecks during the third quarter (July, August, and September), as well as your portion of the employer taxes.

Why it matters: The IRS is notoriously aggressive when it comes to payroll taxes. Because these are “trust fund taxes” (money held in trust on behalf of your employees), failing to file or pay can result in severe penalties. In cases of willful non-compliance, the IRS can even hold business owners personally liable—piercing the corporate veil that usually protects your personal assets.

For businesses operating in California, the state imposes its own strict Q3 payroll requirements. By October 31st, California employers must file with the Employment Development Department (EDD):

• DE 9 (Quarterly Contribution Return): Reconciles the wages reported and the state taxes paid for the quarter.

• DE 9C (Quarterly Wage and Withholding Report): Details individual employee wages, personal income tax (PIT) withheld, and state disability insurance (SDI).

The Advisory Edge: The EDD frequently audits construction firms, professional practices, and retail businesses to ensure workers are properly classified as employees rather than independent contractors. A proactive CPA doesn’t just file these forms—they review your payroll structure year-round to minimize audit triggers and ensure your payroll tax strategy is optimized.

If your business operates in retail, e-commerce, or certain professional services, October 31st is also the deadline to file your Q3 Sales and Use Tax Return with the California Department of Tax and Fee Administration (CDTFA).

California sales tax rules are highly complex, especially for businesses with multiple locations across San Diego, Orange County, and Los Angeles, as local district taxes vary by city. If your business has experienced high growth or expanded into new markets this year, calculating the correct sales tax liability requires precision. Late filings with the CDTFA trigger an immediate 10% penalty on the tax owed, plus accruing interest.

Filing forms on time is the baseline of accounting. But if your CPA is simply functioning as a historian—recording what has already happened and scrambling to meet end-of-month deadlines—they are failing to protect and grow your wealth.

Whether you are managing a real estate development firm, a medical practice, or a high-volume e-commerce brand, you need a financial partner who looks ahead. At Greg Wilson & Associates CPAs, we provide personalized, white-glove service for high-net-worth individuals and complex businesses. We monitor your payroll thresholds, optimize your entity structure, and forecast your tax liabilities long before a deadline approaches.

Contact Wilson & Associates CPAs today to schedule a consultation. Let us handle the compliance so you can focus on building your legacy.

At Wilson & Associates CPA, we combine deep expertise with personalized service to help individuals and businesses stay compliant, reduce risk, and make smarter financial decisions. Whether you have questions about taxes, audits, or long-term financial planning, our team is here to guide you every step of the way.

Contact Wilson & Associates CPA today to schedule your consultation.