State tax filing

You would file 3 returns:

1. A part-year New York return covering income earned during the time as New York resident (including income from all states during this time period);
2. A part-year California return covering income earned during the time as California resident (including income from all states during this time period);
3. A nonresident New York return covering income earned during the time as California resident (including income earned from New York). 

You should prepare your returns in this order:

1. Nonresident New York (always do any nonresident returns first, so you can get the non-resident state tax credit)
2. Part-year California
3. Part-year New York

Here are more info:
https://ttlc.intuit.com/replies/3302342
https://ttlc.intuit.com/replies/3300295