There isn't really an easy answer for that. It may be separate property, but if you purposefully comingle the funds he could argue that it was intended to be a gift to the community. If you later use it to purchase something that you intend to keep separate, "tracing" is allowed to show that you used separate funds, but when they're in the same account it's hard to prove that you weren't using community funds. It is also important to remember that the characterization of property as separate or community is influential but not controlling in a dissolution - all property is before the court for just and equitable distribution. If you're concerned about preserving your own property interests in the event of a divorce, I would strongly suggest having a prenuptial (or post-nuptial) community property agreement that outlines what you brought into the marriage that you intend to keep separate and what you intend to own jointly. Community property is a rebuttable presumption, so the parties are free to change it by agreement, and the court will usually honor that unless it was coerced or blatantly unfair.
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