When are the returns and taxes due (Due dates)?
Answer:  Each state sets its due dates for filing returns and paying taxes.  The due date may not be earlier than the 20th of the month following the reporting period. 

    Example:   Sales tax is collected on transactions that occur in
                     January.  The due date for the return and the payment of
                     those taxes cannot be earlier than February 20th.

When the due date for a return or payment falls on a Saturday or Sunday or legal holiday, the return or payment is due on the next business day.  

If the Federal Reserve Bank is closed on a due date that prohibits you from being able to make a payment by ACH Debit or Credit, the payment will be accepted as timely if made on the next day the Federal Reserve Bank is open.

SSUTA Sections 318 and 319