@George4Tacks "I would propose that they are both residents of one of the two states"

I probably would have done that 50 years ago, too.  Different century, different millenium.

@sjrcpa 

Bonus points for pointing out community-property issue, then not wanting to touch it further.  This is definitely a "send them down the street" return.  

NC resident will probably have to pay tax on half the California income.  NC probably allows a credit for some or all of it.  CA resident pays tax on the other half, and nothing to NC.  Did they do a prenuptial, waiving community rights on income?  No, of course not, they were in love and just wanted to get married.  Or maybe they lived together in Tennessee for 20 years, until now.  

As I said, send them down the street.  Otherwise, get a $1,200 deposit before you start work.  They have it, they just got a check from IRS.