Accounts and records requirement mandates prescribed business and tax recordkeeping, audit triggers, and tax on unaccounted supplies. Every registered person must maintain detailed accounts at the principal place of business recording production, inward and outward supplies, stock, input tax credit, output tax payable and paid, and prescribed particulars; storage facility operators and transporters must keep consignment records. The Commissioner may require additional accounts, permit alternative methods for specified classes, and prescribed turnover thresholds trigger mandatory audit and submission of audited accounts and reconciliation. Failure to account for supplies enables the proper officer to determine tax on unaccounted supplies and apply tax determination and recovery provisions.