I lived in New York the entire year and worked in my New York City office the first half of the year. After that my offices were moved to New Jersey and I worked remotely from my home in NYC 80% of the time, the remainder of the time I worked from the offices in New Jersey.
My employer withheld NY taxes for the entire year (no NJ state taxes were withheld). Furthermore, my W2 lists my office address as the old New York City office address.
My questions are,
Do I need to file an NJ non-resident tax return?
Could I possibly save some money in both state and local (NYC) taxes by filing an NJ non-resident tax return for the half-year 20% of the time I worked in NJ?
How do I make sure I don't get double taxed?