CD347,
It sounds like you only worked or lived in NY part of the year. If that was the case, you would be filing a part-year NY State return. The way tax is calculated for such a return is done in multiple steps: (1) you first calculated how much you would have owed NY if you had lived there all year, (2) you then determine the fraction of that income that was earned in NY, and (3) you multiply the amount in step (1) by the fraction in step (2) to get the tax due to NY State. (There are some smaller details such as apportioning deductions or credits, but that is the basic idea.) This procedure is known as "unitary taxation" and is designed to keep millionaires from splitting their income across many states and claiming low income tax rates in each.
