Part month or pro rata charges are added to your account when you add a service part way through your billing period. It's a way of billing you from the date the service was added until the start of your usual billing period. If you have just received your first bill, take a look at first bill explained to understand a bit more about part month charges when you join us. You may also see part month charges if you add any boosts and extras or change your package. Find out more about this in about part month charges..