Composition levy: option to pay prescribed rate instead of tax, with eligibility limits and penalty for wrongful availing. Composition levy allows a registered person below the prescribed turnover ceiling to opt to pay a prescribed rate in lieu of tax, subject to eligibility conditions excluding specified services, supplies not leviable to tax, inter-State outward supplies, supplies through certain e-commerce operators, and notified excluded manufactures. The option lapses if turnover exceeds the threshold; composition taxpayers cannot collect tax nor claim input tax credit. Wrongful availing attracts tax determination and penalty under the assessment provisions.