Question

What is the Nine-Month Presumption of Residence Rule?
An individual can prove intent to establish a domicile with merely the intention to change their permanent home.
If an individual spends less than nine months in California during a tax year, they are presumed to be a nonresident of the state.
If an individual spends more than nine months of any taxable year in California, they are presumed to be a resident of the state.
The provision for an individual domiciled in California who is outside California under an employment-related contract for at least 546 consecutive days.

Answer 1

Short answer: The nine-month presumption is that presence in California for more than nine months in a taxable year creates a rebuttable presumption of California residency; presence for less than nine months creates a rebuttable presumption of nonresidency. The presumption can be rebutted by other facts, and there is a separate 546‑day employment‑related exception.

Assessment of your four statements
1. False — Mere intention alone is not enough to prove establishment of a domicile; domicile is judged by intent plus objective facts and actions (ties, home, family, business, etc.).
2. True — Spending less than nine months in California in a taxable year gives rise to a presumption of nonresidency (rebuttable).
3. True — Spending more than nine months in California in a taxable year gives rise to a presumption of residency (rebuttable).
4. True (as stated in outline form) — There is a separate provision: a person domiciled in California who is outside California on an employment‑related contract or assignment for at least 546 consecutive days is treated differently (generally presumed nonresident for that period), subject to facts and rebuttal.

If you want citations or sources (FTB publications, Revenue & Taxation Code, or case law), I can provide them.