Only marital (or referred to as "community") property is subject to division in a California divorce, so it is essential to determine what property is considered separate and what is considered marital before attempting to divide property.
Marital property includes all assets acquired by a couple from the date of their wedding to the marital cut-off, or separation date. There are limited exceptions to this rule, such as assets that were gifted to, or inherited by, one party during the marriage. Such property is considered "separate," but may be converted into marital property by commingling, such as when a wife who inherits money from a relative deposits the funds into a joint bank account and the monies are spent jointly by the couple.
Property belonging to one party before marriage is considered separate property, as is property acquired or earned after the couple's date of separation. However, if an asset was earned during the marriage, but paid after the date of separation, such as a performance bonus at work, it is considered marital and thus subject to division as community property. There are many nuances to what constitutes marital versus separate property and oftentimes it is not a clear cut issue. Obtaining legal advice with respect to your particular situation is vital.
The date of separation does not necessarily mean the date one party moved out of the marital home, but when one or both spouses decide the marriage is over, as determined by their words and actions. If the date is unclear, courts in San Diego and elsewhere in California tend to err on the side of a later separation date, so that more property will be considered community property.
Couples can agree, either in a prenuptial or postnuptial agreement, or in a divorce settlement agreement, to consider certain property either marital or separate, even if a California court would decide otherwise.