Filing Due Dates

Form 11
Employer's Municipal Tax Withholding Statement
  Semi-Monthly
Filers
The 3rd banking day after the 15th of each month
and the 3rd banking day after the last day of each month
  Monthly Filers The 15th day of the month following the month withheld
  Quarterly Filers The last day of the month following the end of the quarter:

1st Quarter - April 30th
2nd Quarter - July 31st
3rd Quarter - October 31st
4th Quarter - January 31st

Form 17
Reconciliation of Income Tax Withheld and W-2 Transmittal
  Annually On or before the last day of February following the calendar year in which the taxes were withheld
Form 27
Net Profit Tax Return
  Annually The 15th day of the 4th month following the end of the taxpayer's taxable year
Form 20-EXT
Net Profit Estimated Income Tax and/or Extension of Time to File
  Quarterly The 15th day of the 4th, 6th, 9th, and 12th months after the beginning of the taxable year.