Credit to Grimolde on the official forums.

• Unless you succeed at an Athletics roll (see below) you cannot charge more than your move rate (8 metres for humans)
• A successful Athletics roll doubles your charge movement (rough terrain will modify this roll), if you fail, you move normally, a fumble and you fall down after 1d6 meters of movement.

• You must have at least 4 metres of move left, and must charge a minimum of 4 metres
• You have to be ‘disengaged’ from melee combat
• The charge can be declared on any CA
• You cannot charge and sprint in the same combat round
• The charger gains a damage bonus increase of 1 step (eg. +1d4 to +1d6)
• The chargee may choose to either stand firm and attack, evade, or parry (with weapon size reduced by one)

Example – Bert the Barbarian with 3 CAs and a with a Move rate of 8, moves 2 metres on his 1st CA, he executes a normal attack, costing a 2nd CA, and kills his opponent outright (he doesn’t need to ‘defend’). He then spies another opponent up ahead, and after a successful Athletics roll, charges 10 metres and attacks on his third CA…