Qax is about 400 km northwest of Baku along the main highway through the Alazani valley. Marshrutkas (shared minibuses) run between Baku's Quba bus station and Qax, taking around five to six hours. There are also services from Sheki, which is the nearest sizeable town — about 60 km to the southeast and roughly an hour by road.
The main bus station is in the south of the town. There are also connections to Russia and Georgia from here, though border crossings and service frequency change; it is worth checking locally before you plan around these.
There is no train service to Qax. If you are coming from Tbilisi, the crossing point at Lagodekhi or Kakheti-side roads is the most direct route overland.