The mortgage calculator can be enabled/disabled from Theme Options > Design > Property Page > Mortgage calculator

You can enable Yearly Tax Rate and Homeowners Association Fee fields to be managed for each property in Front End > Submit Listing form

Mortgage Calculator TAX formula

File path

wpresidence/libs/help_functions.php

Front end tax amount is calculated based on the following formula

$monthly_property_tax = $price / 100 * $property_tax_percent / 12;