Thank you @pk. You comments makes sense. I didn't make my question clear though. I was mainly asking regarding the community property tax situation as California is a community property state. By allocation I meant the percentage specified on form8958 (https://www.irs.gov/pub/irs-pdf/f8958.pdf), which is required when filing married separately in a community property state.
For my mom's federal return, she is allowed to allocation 100% of her income to herself as stated in publication 555 (https://www.irs.gov/publications/p555) section "Nonresident alien spouse" conforming to IRC 879 (I have a question on that as well, but later).
For her CA return, since CA doesn't conform to IRC 879, is my mom required to allocation 50% of her income to my dad? That would then requires my dad to file CA 540NR.
Sorry for not explaining clearly earlier. Please use these as the context to my original questions.
