Your accountant in your pocket Use the latest tax calculators, access your cloud accounts or keep up to date with the latest accounting news with Bulley Davey. Please note that the background location of a user’s device is used only when starting the Mileage Tracker module. This is to measure the distance travelled while in use. Thanks to the background location, users can open other apps or make calls without interrupting the trip’s measurements. Continual use can reduce battery power.