Within Natural HR, there is the option to use google to calculate the distance between two postcodes for mileage claims.
Enabling google distance calculation
As an administrator, you will need to go to Administration > Company > Settings > Expenses > Expense settings where under the 'mileage' section, you will need to set 'Use Google Address Lookup' to 'Yes'.
Once enabled, an extra field will appear requesting whether or not employees can overwrite the value which google has entered. If this is set to 'Yes' you will be asked to enter a threshold percentage within which, employee can update the figure without triggering an alert.
If the employee does adjust the distance, a notice will be displayed to the user who is approving the request to inform them that a change has been made.