Dishonour of Negotiable Instrument (Sections 92-100): Non-payment/non-acceptance when due. Causes: Insufficient funds, account closed, signature mismatch, post-dated, stale cheque. Notice: Dishonour notice required to hold prior parties liable. Liability: All prior parties liable for dishonour. Section 138 NI Act: Criminal offense for cheque dishonour; 3 months imprisonment/fine. For accountants, dishonour notice procedures critical for debt recovery.