API Accounting
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Key tax deadlines.

Federal, California, and payroll deadlines most Contra Costa County individuals and business owners need to know. When a deadline falls on a weekend or federal holiday, the IRS deadline moves to the next business day.

  • January 15
    Individuals
    Q4 estimated tax payment for the prior year
  • January 31
    Businesses
    W-2 and 1099-NEC filing deadline (to recipients and to the IRS)
  • March 15
    S-corps & partnerships
    1120-S and 1065 federal returns (or extension Form 7004)
  • April 15
    Individuals & C-corps
    1040 and 1120 returns and any balance due; Q1 estimates
  • April 15
    California
    $800 minimum franchise tax (Form 3522) for LLCs
  • June 15
    Individuals
    Q2 estimated tax payments
  • September 15
    S-corps & partnerships (extended)
    Extended 1120-S / 1065 returns and Q3 estimates
  • October 15
    Individuals (extended)
    Extended 1040 and 1120 returns
  • January 31 / April 30 / July 31 / October 31
    Employers
    Quarterly 941 and California DE 9 / DE 9C payroll filings

Confirm current-year dates on IRS.gov and ftb.ca.gov, or contact us for a personalized calendar.

Never miss another deadline.

Our clients get a personalized deadline calendar every year.

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