It depend on how you pay, if your are up front payment and you have used less than the payment then you are owed and it can be credited to your next bill. if your are on a tariff some companies use the you owe system and its added up to the bill and at the end of the year you can either pay or add to tariff, pay as you go means they owe you no matter what tariff. as you pay before use and any changed in the time you have credit you have this credit back it can be put on by them or they send you a check.
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It depend on how you pay, if your are up front payment and you have used less than the payment then you are owed and it can be credited to your next bill. if your are on a tariff some companies use the you owe system and its added up to the bill and at the end of the year you can either pay or add to tariff, pay as you go means they owe you no matter what tariff. as you pay before use and any changed in the time you have credit you have this credit back it can be put on by them or they send you a check.
On most bills /statements its what you owe --exception is if you over paid or have a credit and that would usually be shown as such