Here are various tax deadlines for the month of October (including the Halloween tax! – haha). 

October 16 is the final deadline to file 2016 regular corporations and personal income tax returns (assuming you got a six month extension to file on or before April 18.)

October 31 is the filing deadline for federal and state payroll tax returns for the 3rd quarter of 2017. It is also the deadline to file 3rd quarter sales tax returns for most states. (this is why Halloween is such a scary evening, not because of ghosts, goblins and sugar hyped children dressed as your worst nightmare.)