California Tax Residency (9-month presumption)

Key parameters
Threshold	9 months (~270 days)
Period / Window	Tax year (1 Jan – 31 Dec)
Counting	Any part of a day
Alternative	Domicile
Additional requirements	Purpose of the stay decides

California decides residence by where your life is centered rather than by a day count. You are a resident if either of these applies:

• Present for other than a temporary or transitory purpose — your reason for being there is open-ended rather than a short visit with a defined end.
• Domiciled in California but away temporarily — your settled home remains California and your absence has a limited purpose.

Both rest on one idea: you are resident where your closest connections are. The Franchise Tax Board weighs your California ties against your ties elsewhere — family, home, license and vehicle registration, bank accounts, voter registration, and how permanent your work there is. Their strength decides rather than their number, and no single one settles it.

Time enters only as a presumption, and it points one way:

• More than 9 months in the tax year presumes residence, though evidence that the stay was temporary or transitory can overcome it.
• Fewer than 9 months presumes nothing. You can be resident on your ties alone, having spent no time in the state during the year.

Two routes out do turn on counting: a visit of 6 months or less can qualify you as a seasonal visitor, and a long absence under an employment contract has its own safe harbor — see Safe harbor for work abroad below.

Someone domiciled in California who leaves on an overseas assignment has a route to nonresidence that runs on a fixed count rather than on the purpose test.

• What it covers — being outside California under an employment-related contract for an uninterrupted period of at least 546 consecutive days, which is 18 months. A spouse or registered domestic partner accompanying them is treated the same way.
• Visits home — returning to California for up to 45 days during the tax year is disregarded, so the period keeps running rather than restarting.
• What breaks it — income from intangibles above $200,000 in any tax year the contract is in effect, or an absence whose principal purpose is avoiding California tax.

Meeting it makes you a nonresident for the length of the absence. It reaches only people who were California-domiciled to begin with, and it needs a genuine employment-related contract behind the absence.

• The presumption only works against you. More than 9 months presumes residence, but fewer than 9 months raises no presumption of nonresidence, so a short stay is not the protection people take it for.
• Crossing the line shifts the work onto you. Below it the state makes its case from your ties. Above it you are the one who has to produce evidence that the stay was temporary or transitory.
• You can be resident having never set foot in the state that year. Domicile carries residence on its own, which is why a day count alone never settles the question for someone whose settled home is California.
• A seasonal visitor can still own a California home. Keeping a house there, holding a bank account for personal spending, or belonging to a club does not by itself cost you visitor status.
• The work safe harbor can fail years into the assignment. Intangible income crossing $200,000 in any single year the contract runs breaks it, even where the day count was met throughout.

Residents are taxed on income from all sources, nonresidents only on California-source income, so an error usually surfaces as out-of-state income left off a return. The Franchise Tax Board charges interest from the original due date and penalties for filing late and for understating a liability, and where no return was filed the window for assessing the tax never starts. Professional tax advice is strongly recommended in situations like this.

A long stay that was still temporary

You spend 10 months in California while a delayed project keeps you there, living in a hotel throughout and keeping your home and family in another state. The presumption attaches, but the circumstances of the stay can rebut it.

A winter that stays within the visitor route

You are domiciled in Illinois, keep your house there year-round, and spend 5 months each winter in a California property you own. Presence stays under 6 months and your conduct is that of a visitor, so the seasonal visitor route holds despite the California home.

An overseas assignment with trips back

You are California-domiciled and take a 20-month contract in Singapore, returning to see family for about 30 days in each tax year. The absence runs past 546 consecutive days and the visits sit under 45 days, so the safe harbor makes you a nonresident for that period.

• Franchise Tax Board — Publication 1031, Guidelines for Determining Resident Status
• Franchise Tax Board — Residency and Sourcing Technical Manual
• California Revenue and Taxation Code — Section 17014