Variance Miles

My husband is an O/O for Stevens Transport. The company has a mileage variance policy. You are allowed a maximum of 8% variance on each trip completed. The trips are calculated zip code to zip code.

For instance:
Actual miles driven - 1506
Load assignment miles given by the company - 1425.
This is within the 8% rule.

Now he only gets paid the 1425, so what happens with the extra 81 miles it took to get to the destination??

The company is quick to charge you if you go over 8%, but doesn't pay you for your actual miles driven.

Is there a way to get the pay for the actual miles??

Thank you in advance.