Apparently there's an NYC Withholding tax change effective July 1, 2017. It _appears_ this may not have been incorporated into the 2017-Q1 TTU. So if that's the case, how come an updated TTU wasn't released?
Fyi:
https://www.tax.ny.gov/bus/wt/rate.htm
Withholding tax changes
NYC Withholding tax change effective July 1, 2017
If you have employees subject to New York City personal income tax who are earning $500,000 or less per year, revised withholding tax computation rules may affect your payrolls made on or after July 1, 2017.
Calculate new withholding amounts using Publication NYS-50-T-NYC, New York City Withholding Tax Tables and Methods (dated 7/17).
For additional information see Important Notice N-17-5, Changes to the STAR Program Personal Income Tax Rate Reduction for Certain New York City Residents