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Essential April 2026 Tax Deadlines for Small Businesses

April is the undeniable heavy-hitter of tax season. For small businesses here in Gilbert, AZ, keeping track of payroll deposits, estimated payments, and corporate returns is a massive administrative lift. At Martinez & Shanken PLLC, our CPAs want to ensure you stay ahead of penalties. Here are the critical business tax deadlines for April 2026.

Mid-Month Milestones: April 15

C-Corporation Returns & Estimates
Calendar-year C-Corps must file their 2025 income tax return (Form 1120) and pay any remaining balance. Need more time? Submit Form 7004 for an automatic six-month extension. Remember, this extends your filing window, not your payment window—you still need to estimate and deposit what you owe. Additionally, your first installment for 2026 corporate estimated taxes is due today.

Payroll & Non-Payroll Withholding
If your business operates under the monthly deposit rule, your March deposits for Social Security, Medicare, and withheld income taxes are due. The same rule applies to non-payroll withholdings.

Fiduciary Returns
This is the final day to file a 2025 calendar year fiduciary return (Form 1041 for Estates and Trusts) or request a timely extension.

Small business team on a video call discussing tax deadlines

Quarterly Wrap-Up: April 30

Form 941 & Q1 Payroll Taxes
Employers must file Form 941 for the first quarter of 2026. Deposit any unpaid taxes under the accuracy rules. If your liability is under $2,500, paying in full with a timely return is acceptable. If you already deposited fully and on time, your filing deadline stretches to May 11.

Federal Unemployment Tax (FUTA)
If your FUTA tax owed through March exceeds $500, deposit those funds today.

Holidays and Disaster Relief

When deadlines land on a weekend or legal holiday, they shift to the next business day. Furthermore, federally declared disaster areas often receive automatic extensions. Verify your geographical eligibility through these official resources:

Missing a deadline can derail your cash flow with unnecessary penalties. If you need help managing these filings, contact the small business accounting team at Martinez & Shanken PLLC today to schedule a consultation.

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1560 W Warner Rd Suite 200
Gilbert, Arizona 85233
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