Hello, as I completed my NY State e-file, your software presented me with an MCTMT worksheet and said I have to mail it in, but did not tell me where to send it.

The MCTM Tax is no longer filed on its own return, it used to be filed on form MTA-6.  Now it is computed using the MCTMT Worksheet, and the resulting tax is reported on the main form, IT-201 line 54, or IT-203 line 52.   Keep the worksheet for your records, there is no need to mail it in. 

Hi chatellm, there are a few ways you can send in your MCTMT worksheet and pay your balance due: 

• File and pay online: Web File Form MTA-305, Employer's Quarterly Metropolitan Commuter Transportation Mobility Tax Return and pay directly from your bank account. (To Web File you must create an Online Services business account.)
• File paper Form MTA-305, Employer's Quarterly Metropolitan Commuter Transportation Mobility Tax Return, and pay by check or money order.
• You can choose to pay this tax using the PrompTax program if you currently use the PrompTax program to file New York State withholding tax. See employers participating in the PrompTax program for details.
• You do not have to attach a listing of covered employees when filing and paying the tax.
  
  

Source: https://www.tax.ny.gov/bus/mctmt/emp.htm