I live in MA, but did an internship in CA in 2016. Filed electronically the tax returns for IRS and 2 states, applying the CA tax amount as a credit in the MA return, as it is usually done. However, while Fed and CA went fine, the MA dep. of revenue still can't process my return, because they don't see where did this credit came from.
My understanding is that the electronic tax prep systems automatically send all the forms and returns everywhere they belong, and the user has little control of it. How is it possible then that MA does not know about my CA tax? If I file an MA amendment (with the same numbers), how do I make sure that the information about my CA tax is also sent along? All my tax forms are already in the tax prep system, so I have nothing extra to add.