Section 771(a) provides that the earnings and accumulations of a spouse — and of the minor children living with or in the custody of that spouse — after the date of separation of the spouses are the separate property of the spouse. It is short, and it makes the date of separation one of the most consequential facts in a California divorce.
Everything earned before that date is community property under § 760; everything earned after it belongs to the earner. A bonus, a commission, a share award or a sale that lands on one side of the line rather than the other can move a great deal of money, which is why the date is contested far more often than the rule. Separation is not simply the day someone moved out: the Family Code defines the date of separation by reference to a complete and final break in the marital relationship, shown by one spouse expressing the intent to end the marriage and by conduct consistent with that intent, and couples can separate without either of them leaving the house.
The word "accumulations" is wider than "earnings" and covers what the post-separation earnings become. Subdivision (b) is a narrow carve-out: the earnings and accumulations of an unemancipated minor child from a contract of the type described in § 6750 — the statute governing contracts for artistic, creative and athletic services by minors — remain the sole legal property of the child. Establishing the date of separation on the evidence, and characterising anything that straddles it, is squarely a matter for a family lawyer.