Acceptance of reassessed customs value under protest does not...

Acceptance of reassessed customs value under protest does not extinguish the importer's independent statutory right to challenge the reassessment. Written acceptance relieves the proper officer of issuing a speaking order but does not create estoppel against statutory rights in taxation. Rejection of a declared transaction value requires written communication of the grounds for doubting its truth or accuracy. Enhanced valuation cannot rest solely on undisclosed alleged contemporaneous imports; the importer must receive the relevant comparable-import data and comparability particulars. Redetermination of value must follow the prescribed sequential valuation rules after the declared value is validly rejected.