un·der·charge 
/ˌʌndɚˈtʃɑɚʤ/ verb
un·der·charg·es; un·der·charged; un·der·charg·ing /ˌʌndɚˈtʃɑɚʤ/ verb [+ obj] : to charge (someone) too little for something : to ask (someone) to pay too little money for something
▪ They undercharged him for the book by $5. — opposite overcharge
▪ They undercharged him for the book by $5. — opposite overcharge
