The act of adding an extra amount on top of an existing sum or condition; tacking on an additional charge, pay, tax, etc.
会社は従業員のベース給に一時金を上乗せした。
The company added a bonus on top of employees' base salaries.
諸経費が上乗せされて、請求額が増えた。
With additional expenses added on, the billed amount increased.
消費税が上乗せされる前の価格を確認してください。
Please check the pre-tax price before consumption tax is added on top.