Time limits for customs duty recovery require an opportunity to be heard and allow supervisory extension where justified. Procedures govern recovery of unpaid, short levied or erroneously refunded customs duties, interest, refunds and drawback where demand notices must be issued within statutory limitation periods; the proper officer shall, after allowing the concerned person an opportunity of being heard and considering representations, determine the amount of duty or interest within prescribed periods, subject to supervisory extension, and officers conducting inquiries or audits must transfer relevant documents and reports to the proper officer or assigned officer for exercise of recovery powers.