One way a party in a lawsuit in California is able to verify information is called Request for Document Production, which is a formal request for the opposing party to produce specified paperwork. A request for tax returns allows you to compare what your spouse is telling you with what he told Uncle Sam.
California statutes permit discovery of any non-privileged matter that is relevant to the legal action. You should limit your request for tax returns to the years relevant to your divorce, which depends on the length of your marriage and the financial issues in the divorce.
California divorce law mandates that divorcing spouses need to exchange certain financial information. This procedure is termed disclosure. The information that must be exchanged includes the two years of tax returns before separation. You must submit a discovery request to your spouse to receive any older tax returns.