State tax filing

Upon further review, you may be a part-year resident of NYC.  Information provided by the New York Department of Taxation and Finance is somewhat misleading.  For example, based on the information from their FAQ page, you would not be considered a resident/part-year resident of NYC because, as it states:

 ...You are a New York City resident if:

• your domicile is New York City; or
• you have a permanent place of abode there and you spend 184 days or more in the city.

FAQs About Filing Requirements

Based on what you indicated in your post, your domicile is not NYC.  Moreover, it does not appear that you spent 184 days or more in NYC.  Therefore, based on the FAQ page referenced above, you would not be a resident of NYC.

However, NY also provides the following information about who is a NYC resident which appears relevant to your tax situation.  (Note, according to the Department of Taxation and Finance, substitute New York City for New York State)

You are a New York State resident for income tax purposes if:

• your domicile is New York State (see Exception below); or..

While your domicile is not in NYC, you need to also review the Exception which provides the following:

Exception: If your domicile is New York but you meet all three of the conditions in either Group A..., you are not a New York State resident.

Group A

1. You did not maintain any permanent place of abode in New York State during the tax year; and
2. You maintained a permanent place of abode outside New York State during the entire tax year; and
3. You spent 30 days or less (a part of a day is a day for this purpose) in New York State during the tax year.

It appears you meet number 1 and number 2 in the Exceptions above.  However, it does not appear that you meet number 3 given that you spent several months in NYC while attending graduate school.  Thus, based on the above NY Income Tax Definitions, it appears you would be considered a part-year NYC resident.  

You might consider contacting the NY Department of Taxation and Finance to confirm whether you are a NYC part-year resident for income tax purposes. However, because the Income Tax Definitions page provides more detailed information about residency, it may take precedence over the FAQ page.    

NY Income Tax Definitions

@sowsun