I am staying with my girlfriend in NYC (her apartment - I don't pay rent) and I am a longtime California resident. I have kept my apartment (rental) in California, and have been in NYC for the past 8 months (on and off). I just started a full time job here and I thought I research the issues surrounding my tax scenario. A Google search lead me here, and to a similarly named thread involving a different set of conditions.

I have a California driver's license, and do not want to lose my state residency in California. Can I put my California address on my w-4. What are the tax implications of doing so. Will the employer have a problem with this (will the finance department bounce it back, or question it?). Separately I'm concerned if this will look bad in the eyes of the employer (aka corporate suicide?). Or if this is a more typical scenario than I initially imagined. If it is typical, what should I expect back from the employer (any push back? Questions?). And what are reasonable answers to such without overstating the inherent boundaries of the situation if that makes sense (aka, what's the simplest and/or shortest answer that will make sense to the employer and keep them on board with me as a new hire?

I've been working there 3 days already and I they're pushing me to get the w-4 back to them asap (understandably?)

Thanks much,
Pt

Your state of residency is determined by where you live, not what your driver's license says, or what you wish it to be. From your description it sounds like you have been an NYC resident for the past 8 months. So you should show your NYC address on your W4 and be prepared for your employer to withhold both NY State and NY City income tax. The good news is that you will not owe CA anything on income earned in NYC from the time you moved out of CA. For tax year 2008 you will file a part-year resident return for CA, covering the period you lived there, and a part-year resident return for NY State as well.

Question - what is your motivation for not wanting to lose your California residency? What does it matter?