Tax collection at source penalty and prosecution framework covers non-collection, non-payment, reasonable cause, and graded criminal exposure. Failure to collect tax at source under Chapter XVII-BB attracts penalty under section 271CA equal to the tax not collected, with the power to impose penalty shifting to the Assessing Officer for penalties imposed on or after 1 April 2025. Failure to pay collected tax to the Central Government attracts prosecution under section 276BB, subject to graded punishment thresholds for later defaults and an exception where payment is made by the prescribed statement-filing deadline. The reasonable cause defence under section 273B applies to section 271CA.