California tax deadline: When are small business taxes due?

California tax deadlines – Key takeaways

• Most California small businesses must file taxes by April 15, though S Corps and partnerships typically file by March 15. Extensions move the deadline three months out from the original tax deadline.
• Quarterly estimated tax payments are generally due April 15, June 15, September 15, and January 15, with additional employment tax filings required if you have employees.
• Businesses impacted by the 2025 Los Angeles County wildfires have until October 15, 2025, to file federal returns and make payments, including quarterly estimates and payroll taxes.

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According to the US Small Business Administration, California has more than 4.3 million small businesses. That’s 99.8% of all California companies! For this state’s burgeoning community of small business owners, tax season is a pivotal period that requires careful navigation through a maze of California tax deadlines. If you are a small business owner wondering, “When are taxes due in California?” look no further. Below, we’ll cover important business tax deadlines to help you stay on top of this crucial activity.

Note on the impact of the 2025 California wildfires

The Internal Revenue Service (IRS) announced on January 10, 2025, that California taxpayers affected by the wildfires in Los Angeles County have until October 15, 2025, to file their business and personal federal tax returns, as well as make payments.

With the disaster declaration issued by the Federal Emergency Management Agency (FEMA), taxpayers who reside in or own a business in California qualify for tax relief. The extended deadline applies to federal income tax returns and payments normally due on April 15, 2025. It also applies to estimated tax payments normally due on January 15, April 15, June 16, and September 15, 2025.

The new October filing deadline also applies to these businesses and their tax due dates:

• Quarterly payroll and excise tax returns – normally due January 31, April 30, and July 31, 2025.
• Calendar-year Partnership and S Corp returns – normally due March 17, 2025.
• Calendar-year Corporation and fiduciary returns and payments – normally due April 15, 2025.
• Calendar-year tax-exempt organization tax returns – normally due May 15, 2025.

If you are an affected taxpayer and still receive a late filing or late payment penalty notice that has the original filing, payment, or deposit due date that falls within the postponement period, contact the number on the notice to request the IRS abate the penalty. A Block Advisors Small Business Certified Tax Pro can also help guide you through this process.

When are taxes due in California?

When it comes to tax compliance, small business owners must know when taxes are due in California. In this section, we’ll outline the key deadlines, including the California business tax filing deadline for 2025. Every California entrepreneur should mark their calendar with this date to ensure a seamless tax filing process.

From income tax deadlines to quarterly tax deadlines to employment tax deadlines for small businesses, staying informed about these California tax dates is crucial. Knowing these milestones helps small businesses stay on track and avoid any last-minute rush or penalties. Keep reading to ensure you are aware of federal and California business tax filing deadlines.

Income tax deadlines

Most small businesses need to file federal income taxes annually. These taxes are based on the revenue your company earns each year. The form you need for your income tax return depends on your business structure. You may use one of the following Internal Revenue Service (IRS) forms:

• Sole Proprietors or LLCs – IRS Form 1040 using a Schedule C
• C Corporations – IRS Form 1120
• S Corporations – IRS Form 1120S
• Partnerships – IRS Form 1065 

For many small businesses, including Sole Proprietorships, Single-Member LLCs, and C Corporations, the business tax deadline is April 15. However, keep in mind that some small businesses have an earlier tax deadline. This includes S Corporations, Multi-Member LLCs, and Partnerships. So, if this is how you’re structured, you’ll need to finish filing your return by a different tax deadline – usually March 15. Generally, the California tax deadline for income tax aligns with the federal deadline. If the deadline falls on a weekend or holiday, it may shift to the next business day.

If you found yourself needing additional time to file your income taxes when the California tax deadline came around, you may have filed a tax extension using IRS Form 7004. If this is the case, you have until October 15, to file your individual or corporate tax return. Again, if the tax extension deadline falls on a weekend or holiday, it pushes to the next business day.

Quarterly tax deadlines for small businesses

The quarterly estimated taxes you must file also depend on your business structure. Sole proprietors, partners, and S Corporation shareholders who expect to owe more than $1,000 at tax time are generally required to make federal quarterly estimated tax payments. This recurring filing is in addition to their annual income tax filing. C Corporations who expect to owe $500 or more when filing their corporate income tax return also generally are required to make federal quarterly estimated tax payments. Read our article to learn more about federal estimated tax payments.

Some important federal quarterly tax dates for 2025 to keep in mind:

• April 15, 2025 – 1st quarter (Q1) estimated tax payment due
• June 16, 2025 –2nd quarter (Q2) estimated tax payment due
• September 15, 2025 –3rd quarter (Q3) estimated tax payment due
• January 15, 2026 – 4th quarter (Q4) estimated tax payment due

NOTE: The federal estimated tax due dates are generally April 15, June 15, September 15, and January 15. When the date falls on a weekend or holiday, the deadline is moved to the next workday. If you’re wondering about other business tax deadlines, see a more comprehensive list of all federal business tax deadlines.

Though the California tax deadline for estimated tax payments often matches the federal deadline, some years are different. Make sure you are aware of the current year’s California tax deadlines and forms for California quarterly estimated taxes, which are available on the California Franchise Tax Board website.

If you’re feeling unsure, a Block Advisors certified small business tax pro can help you understand which forms and deadlines you need to consider.

Employment tax deadlines

If your business has employees, you’ll need to report their wages, tips, and other compensation. To do this you use IRS Form 941 for federal purposes, filing it with your usual quarterly tax return. This form reports employer payments and FICA taxes withheld from your employees’ paychecks quarterly. In addition to these, you may also need to file state forms by the California tax deadline.

Don’t confuse this with employee and contract worker-centered forms that require annual filings, such as IRS Forms W-3, W-2, and 1099s.

Get more help with California tax deadlines

It’s important to be aware of business tax deadlines. If keeping track of both the federal and California business tax filing deadlines has you feeling overwhelmed, we are here to help. Block Advisors certified small business tax pros are available all year long, remotely and in person, to help you nail your tax return.

Find out how to save time and money while keeping your small business taxes on track.

Block Advisors experts are also available to assist you with other parts of your small business to-do list. Our bookkeeping, payroll, incorporation, and business formation services are designed with small business owners like you in mind. As always, our services are backed by guarantees to give you peace of mind.

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This article is for informational purposes only. The content may not constitute the most up-to-date information and should not be construed as legal advice.