In Indiana, you have until end-of-office-hours on December 31 to file for the homestead exemption. If you do not file (or verify that you have proper exemption status), you may be contacted by your friendly County Auditor that your homestead exemption could be terminated.
Homestead exemption reduces your property taxes by reducing the assessed value of your residence. In order to qualify, you must provide tax ID information for the legal owners of the property. You cannot claim a homestead exemption on more than one residence (so you will have to pay higher taxes on that Indiana Beach vacation home)