Voluntary payment of customs duty: interim payments attract prescribed interest and are adjusted against the final assessed duty. Voluntary payment of customs duty during provisional assessment is permitted upon written intimation to the proper officer; such payment must include interest at the prescribed rate from the first day of the month in which the duty was provisionally assessed until payment. Bond terms and security remain unchanged and no refund is allowed until finalisation. Interim payments do not attract further interest from payment date to finalisation, but interest is recalculated from the first day of the provisional assessment month to the payment date upon final assessment, and interim duty and interest are adjusted against the final liability.