Heads, terms and concessions defined once per class and reused all year. Get this right and invoicing is a run; get it wrong and every invoice is an argument.
Heads and frequencies
A fee head is a thing being charged — tuition, transport, examination, laboratory. Each is set per class and academic year with its own amount, due date and frequency: monthly, quarterly, half-yearly, annual or a one-time charge.
Concessions as rules
A concession is a percentage or a fixed amount, and it can apply to particular heads rather than the whole bill — a staff ward concession on tuition but not on transport. It is defined once and attached to the students who qualify.
Transport that follows the stop
Transport fees are carried by the route and stop a student is allocated to, so a child who joins the bus in July is billed from July rather than from a note in the office diary.