All payments received by the Treasurer's office AFTER that installments due date are considered late UNLESS:
1 - Your properly addressed payment envelope CLEARLY displays a United States Post Mark dated on or prior to the due date
2 - Your properly addressed payment envelope has been deposited with a nationally recognized express parcel carrier on or prior to the due date
Penalty calculation instructions are printed on the front of your bill.
See IC 6-1.1-37-10 for full code on post mark and penalty calculation