Interest on delayed excise duty and wrongful credit use accrues and is recoverable under specified timing rules. Interest is chargeable on delayed or short paid excise duty, wrongful Cenvat credit use, and excess collections; normal delayed payment interest runs after a three month grace period from the date of duty determination, while fraud or suppression triggers interest from the first day of the month following non payment. Administrative uniformity directions may waive interest if paid in full without reservation within a short window; interest follows appellate adjustments and self assessment non payment rules. The department pays interest on delayed refunds after three months; interest is excluded on fines and penalties and interest on interest is not payable.