Excise duty payment timing mandates deferred payment with interest and forfeiture consequences for assessees who default. Rule 8A requires duty on specified goods removed in the transitional period to be paid by the prescribed deadline and is deemed discharged only when the amount is credited to the Central Government's account by that date; payment made as prescribed is treated as paid for purposes of the rules and credit allowed. Failure to pay timely attracts notified interest on the outstanding amount and forfeiture of the instalment facility for a two month period or until dues are paid, during which duty must be paid by debiting the account current or the clearance will be treated as without payment.