Oh-no! I am late with my quarterly payment. When will I be charged interest?

Interest is charged 30 days after each due date (on the 1st of the month). For example: The property tax due date for the first quarter is August 31. Postmarks are accepted if marked before midnight on August 31. Interest will be charged on October 1 if payment is not received by September 30 and is not postmarked by August 31. Postmarks are not extended to the 30-day "grace" period.