If I live in CA and work remotely for a company in NY what is the "NY source portion" in income and deduction?

[KeshaH]

It depends.

New York has what's called the Convenience of the Employer rule, which means that if your employer's primary office is in New York, the income you earn as a remote worker may still be considered New York income unless your remote work location qualifies as a bona fide employer office. If that's the case, all of the days that you work for that employer would be considered NY work days and all of your income from that employer would be NY source income.