Underpayment (noun)

A payment that is less than the amount that is due or expected.

Origin:

From under- (below) + payment (the act of paying).

Examples:

1. The employee received an underpayment due to a mistake in calculating the salary.
2. He was charged with underpayment of taxes.
3. The customer made an underpayment on their bill.
4. The company was accused of underpayment of wages.
5. The vendor was penalized for underpayment of rent.