Fiancé filed married filing joint. We’re in CA & not legally married. Advisor said it was fine but everywhere i read it says it’s not. Does an amendment need to be done?

[Unsuretaxpayer]

He works, I’m home with children. Advisor said as long as we prove we’ve been together all these years it’s okay. But CA does not recognize common law marriage. And all other paperwork we do we say were single, because legally we are. 

[macuser_22]

That is correct - CA does not recognize common law marriage - you need a new advisor.

If not married as of the last day of the year, then you can only file single or head-of-household if you qualify.

Unfortunately this is not a simple matter of amending because the tax law does not allow changing a joint return after the April 15 due date - the IRS must declare the joint return a "invalid joint" return.   This is not a do-it-yourself matter.  See this excellent answer by rjs when this came up last year. (The answer was about divorced persons but the procedure is the same for persons never married).

https://ttlc.intuit.com/replies/6972240