Mailing address changes should be made through the Hamilton County Real Property Department of the Auditor's Office. Completing a Mailing Address Change Form with the Post Office will not notify the Real Property Department of your new address. Failure to notify the Real Property Department before March may result in your tax bill not being delivered to the correct address. All taxpayers are responsible for paying property taxes regardless of receipt of the mailed bill. Submit your address change online, fax it to 317-776-9682 or mail it in to the Real Property Department.