I think I know a little about community income, having practiced in Arizona for the last 45 years.  I have many married clients with separate property, either because they owned it before marriage and did not commingle it, or because they have prenuptial or postnuptial agreements.  If you can't answer a simple question about how you know it's not separate property, then I also wonder how much you know about your client.  You're not doing returns for both ex-spouses, are you?