In California, from the date of separation (whether a physical separation or a stated intent to end the marriage), all property earned is your separate property and can be spent however you wish. If you are spending money on a marital asset, then the other party may owe you for the half he was obligated to pay (such as a mortgage) if he didn't cover his half. However, this is a complicated area of the law and you will likely want to consult with an attorney to determine the true nature of each asset and the date of separation.
Answered on Jan 11th, 2013 at 1:03 AM