Several questions to answer. I'll try to do so one at a time.
Do you need to calculate your income from mid June to the end of the year for California? Yes. California's position for telecommuter taxation during COVID is that if you were physically present in California for at least two weeks, then you pay California tax on the income you worked while you were there. Since your facts are that your California stay began in mid June and went to the end of the year, you will pay CA tax on this time period. (Keep in mind that your income from January to mid February is also likely taxable in California if you were living there or working there at the time).
Should you file as a nonresident or a part-year resident? With two periods of "residency" in the year, it is more accurate to select nonresident. If on a part-year return the state asks you to report a move-in or a move-out date (as most do), it is impossible to report a move-out date in February and a subsequent move-in date later in the year. So the most accurate status is non-resident.
Are you on the hook for any employer tax obligations during this time? I'm not sure I understand what you mean by employer tax obligations. On face value the answer is no because only the employer can be on the hook for employer tax obligations in California. But if I'm not understanding this part of the question correctly, please feel free to clarify with additional detail as to what you mean.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
