/**
 * Calculates the late fine for a student fee based on payment delay.
 *
 * Rules:
 * - Returns 0 if the fee status is `CANCELLED` or `REFUNDED`.
 * - Returns the existing `fee.fine` value if it is set and greater than 0.
 * - Returns 0 if `perDateRate` ≤ 0 or `fee.amountDue` ≤ 0.
 * - When payment is in the same calendar month as the due date, fine days = payment day - dueDateLength.
 * - When payment crosses into a later month, fine days = days from the 1st of the due month to the last day of the month before payment.
 * - Fine amount = fineDays × perDateRate × (amountDue / amount), rounded to 2 decimal places.
 *
 * @param fee - The fee object containing amount, amountDue, dueDate, optional fine and paidAt, and status
 * @param dueDateLength - The day of the month after which a fine starts accruing (e.g. 10 means fine starts on the 11th)
 * @param perDateRate - The fine rate per day
 * @param asOf - Optional reference date used when paidAt is not provided (defaults to current date)
 * @returns The calculated fine amount rounded to 2 decimal places
 */
declare const calculateStudentFeeFine: (fee: {
    amount: number;
    amountDue: number;
    dueDate: Date;
    fine?: number | null;
    paidAt?: Date | null;
    status: string;
}, dueDateLength: number, perDateRate: number, asOf?: Date) => number;

export { calculateStudentFeeFine };