The union dues will automatically be transferred over to your IT-196, which is your resident, nonresident, and part-year resident itemized deductions form onto line 21 (Unreimbursed Employee Expenses - job travel, union dues, etc).
Unfortunately, while they are technically 100% deductible this year, they are only such if you Itemize your returns on your New York state return.
If your Standard Deduction is still higher than the sum of all of your Itemized Deductions, it will automatically apply your standard deduction on line 34 of your New York IT-201 return in order to give you the most benefit. This is why you may not see anything change when you enter the information.
