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California small business finance, explained

Deadlines, guides and plain answers for running the financial side of a business in California. Written by the people who do this work every day, kept current, and free whether or not you ever become a client.

Written for CaliforniaFederal and state, side by side

What are you trying to sort out?

Starting a business

Entity choice, registration, and what’s cheaper to set up right than to fix later.

Books behind

What catching up involves and how to stop it recurring.

First employee

What changes the day someone goes on the books in California.

Tax season coming

What to gather and what to decide before year end.

California small business deadlines

The dates that catch people out. Federal and California.

The full tax calendarEvery federal and California date, month by monthOpen the calendar
Federal and California small business filing and payment deadlines
WhatWho it applies toDate
Quarterly estimated tax, Q1Self-employed and pass-through ownersApril 15
Quarterly estimated tax, Q2Self-employed and pass-through ownersJune 15
Quarterly estimated tax, Q3Self-employed and pass-through ownersSeptember 15 (federal only)
Quarterly estimated tax, Q4Self-employed and pass-through ownersJanuary 15 of the next year
W-2s to employeesAnyone with employeesJanuary 31
1099-NEC to contractorsAnyone paying contractorsJanuary 31
Partnership and S-corp returns1065 and 1120S filersMarch 15
C-corp and individual returns1120 and 1040 filersApril 15
California Statement of InformationCorporations and LLCsBy the end of your registration month: every year for corporations, every two years for LLCs

Last reviewed October 2026. Dates move when they fall on a weekend or holiday. If one of these matters to you, check the calendar or ask us.

See the full tax calendar

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Three pieces worth reading first.

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Recent articles

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Case studies

Coming later[GAP: case studies — only one item exists and it is an article, not a case study. Needs at least three real client stories with permission before this section or /case-studies/ goes live.]

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