Usually most colleges takes the fees after the due date with some additional charge namely the fine. So if you want to pay your fees after the due date then you need to contact your college and you have to pay the fees with some fine.

Now if you are talking about any entrance examination or competitive examination, then if you aren't able to pay the fees on the last date, then you have nothing to do. You can't sit for the examination.

As you didn't mentioned the scenario I give you some of the general information.

Have a great eve!