Customs duty collections from buyers must be credited to the government and adjusted against final duty liability. Amount collected from a buyer in excess of the duty assessed, determined, or paid on goods, or collected as customs duty on exempt or nil-rated goods, must be credited to the Central Government. If payment is not made, the proper officer may issue a show-cause notice and determine the amount due after considering any representation. Amounts so paid are adjusted against duty on finalisation of assessment, and any surplus is dealt with under the refund provisions applicable to customs duty.