California's 9-month rule + facts and circumstances test, explained

California is the trap people don't see coming. There is no clean 184-day threshold like New York. Instead, the Franchise Tax Board (FTB) uses a 9-month presumption plus a facts-and-circumstances test — and the burden of proof is on you. If you split your time between California and a no-tax state, you need to track every day and document every tie.

The 9-month presumption

California Revenue and Taxation Code § 17014 establishes a presumption: if you spend more than 9 months in California in a tax year, you are presumed to be a California resident. Any portion of a day counts as a day of presence. Nine months ≈ 274 days, so once you cross that line, you're presumed in.

The facts-and-circumstances test

California's domicile test asks: where is your closest connection? The FTB looks at every connection you have to California and weighs them against your connections elsewhere. There's no single threshold; it's a holistic review. Connections the FTB cares about:

• Where you spend the most time (day count matters even without a hard threshold).
• Where your home is — owned, rented, or even available to you.
• Where your spouse and minor children live.
• Where your driver's license, voter registration, and vehicle registrations are.
• Where your bank accounts, primary doctor, and dentist are.
• Where your business interests, partnerships, and place of work are.
• Where your social, religious, and recreational ties are.
• Where your wills, trusts, and other legal documents are filed or domiciled.

A common scenario: someone moves from California to Texas, registers their car, gets a Texas license, but keeps the Bay Area home and visits frequently. The FTB will count the home, the visits, and any business ties as evidence of continued California residency. Without a contemporaneous day-count record, you'll lose the audit.

The 546-day safe harbor (for departing residents)

California has one true safe harbor: the 546-day rule for residents who leave on an employment-related contract. If you're absent from California for an uninterrupted 546-day period under an employment-related contract, you can be treated as a non-resident — but only if you're not in California for more than 45 days in any tax year during the absence, and your spouse and dependents either come with you or stay back without significant California ties.

What counts as a day in California?

Like New York, California counts any part of a day as a day of presence. A flight that lands at SFO and continues to Hawaii counts as a California day if you cleared customs and walked through the terminal. The FTB's audit guides explicitly include layovers and partial days.

• Counts: any presence, even a few minutes.
• Doesn't count: days you were a passenger in transit through California airspace without landing.
• Mixed: days you returned home (e.g., LAX layover) typically do count.

How a California residency audit works

FTB residency audits are slower than New York's but just as thorough. You'll be asked to complete a Residency Questionnaire (FTB 4600 series). The auditor will pull credit card records, ATM withdrawals, EZ-Pass-equivalent toll data (FasTrak), cell-tower records, utility bills, and even social media. They'll reconstruct your day count and challenge anything that's not contemporaneously documented.

How to track for California

Because California's test is facts-and-circumstances rather than day-count, you actually need more documentation than you would for New York — not less. Tax Days tracks every California day, projects when you'd hit the 9-month presumption, and exports a per-state PDF that you can hand to your tax preparer or your auditor.

More importantly, a contemporaneous record dated before the audit is far more credible than a reconstruction. A defensible position on the facts-and-circumstances test starts with a defensible day count.