Q. Will I have to file a CA return and owe any California (CA) income tax if I work remotely in CA on a temporaray basis?
A. Yes, but "nobody" does*. See http://money.cnn.com/2013/06/28/pf/taxes/business-traveler-tax-threat/
Even if you do decide to file a CA return, CA will give you a credit for the tax you paid to NY on the same income ($7692).
Q. Will I owe California state income tax as if I only made $100,000*(4/52)=$7692 in the year?
A. Yes.
*If you live in a state without an income tax (e.g. FL or TX), and your employer was located there too, it’s more likely you should file in the work location state (CA). You can't use the "it all comes out even" rationale for not filing.
