Self-assessment in central excise: assessees determine duty on invoice-based clearances while department conducts selective audits. The Manual supplements the Central Excise Rules, 2002 and prescribes nationwide procedures requiring adherence unless Commissioner or Board approval permits deviation. It records the shift from supervised clearances to invoice-based clearance and a continuing self-assessment regime where assessees declare classification, value and quantify duty at clearance, subject to departmental scrutiny and selective audit. It also mandates taxpayer assistance units, acceptance of electronic communications, time-bound replies to trade queries, and targeted support for small-scale manufacturers.