The Next Physical Service Date is when you must visit a Smart Start location to perform a service and calibration on your device.
The Next Payment Due Date is when your next payment to Smart Start is due.
For Ignition Interlocks and non-cellular IN-HOMs, you can make an online payment to advance your Next Payment Due Date. Keep in mind that you will still need to visit a service center by your Next Physical Service Date.
For SMART Mobile, you can make an online payment to advance your Next Payment Due Date. The device will also change the Next Physical Service Date accordingly. NOTE: The SMART Mobile device will require service/calibration every six months.