How to disable a check box using php code?

I am creating an application for fee collections in a school.

I want to disable the check box of a month, when the complete fee of that particular month is paid or collected by a fee collector.

For example, if June fee is 500, July is 500 and Aug is 500 and so on. If a parent comes and pay 750, I want to disable the June Check box and keep the other check boxes enabled as the fee is still due in other months.

Could you please help me in getting the solution for this?

Thanks in advance. KJ.