State tax filing

That depends on whether, under New York law, you are a resident, part-year resident or non-resident with NY source income.  Even if you relocate to Florida, NY will continue to tax your income if you continue to be resident, part-year resident, or a non-resident with NY source income.  Thus, for tax purposes, it's important to understand NY's residency rules.  

Generally, you are considered a New York State resident for income tax purposes if you are domiciled in the state. For most people this is straightforward: the primary residence where you live is both your state of domicile and the state in which you are a resident for tax purposes. However, you can still be considered a resident of New York State for income tax purposes even if you are not domiciled in the state. 

In general, your domicile is your permanent and primary residence that you intend to return to and/or remain in after being away (for example, on vacation, business assignments, educational leave, or military assignment).

Residence means a place of abode. An individual may have several residences—e.g., houses, apartments, condos, and/or other places to live or physical dwellings in which they reside—and some may be in different states.

While you may have multiple residences, you can only have one domicile. An individual may live in a certain residence for a temporary period of time, which could be an extended period of time, but if it’s not the place they ultimately attach themselves to and intend to return to, it’s still not their domicile.

So, let's say you relocate to FL.  Can NY still tax your RSU's?  No, if you have made FL your domicile.  But there is one situation when even if your domicile may be in FL that you could still be subject to NY taxes.  The NY Department of Taxation and Finance addressed this question as follows:

Can I be a resident of New York State if my domicile is elsewhere?

You may be subject to tax as a resident even if your domicile is not New York.

You are a New York State resident if your domicile is New York State OR:

• you maintain a permanent place of abode in New York State for substantially all of the taxable year; and
• you spend 184 days or more in New York State during the taxable year. Any part of a day is a day for this purpose, and you do not need to be present at the permanent place of abode for the day to count as a day in New York.

In general, a permanent place of abode is a building or structure where a person can live that you permanently maintain and is suitable for year-round use. It does not matter whether you own it or not.

FAQs from the NY Department of Taxation and Finance

Therefore, if FL does become your domicile and the above guidance from the NY Department of Taxation and Finance does not apply to you, then NY cannot tax your RSUs.  Keep in mind there could be some allocation that needs to be made based on your time in NY.  

@nyc_taxpayer