How to record late payment charges (electricity bill , telephone bill)

sir my question is to you how to record late payment charges and which period this late payment charges be accounted let say i got electricity bill of 800 rs of aug month in sep 10 and the due date to pay bill is 15 sep . the bill has mentioned that after due date 50 rs extra will be charged if i pay bill after due date i have to pay 850 rs (including late payment charge of rs50) so i would like to know who to record this transaction and please specify me which month this late payment charges belongs to ?? also tell what are the journal entry i need to do ?? and thanks in advance