Get your taxes done using TurboTax

When you go through your New York return, you will see a screen that references New York Income Allocation:

This screen shot is for a non-resident of New York, but you will see a similar one if you are a resident and earned income in other states.

When you answer "yes" to the question regarding income being earned in states in addition to New York, you will be asked to enter the New York portion of the income reported on your federal return. Those numbers will establish the percentage to use to adjust your tax to the correct amount for New York.