Tax deduction at source requires specified public entities to withhold, remit promptly and issue certificates to suppliers. Specified government entities and notified persons (the deductor) must deduct tax from supplier payments above the statutory threshold, excluding specified inter state supplies and tax components. The deductor must remit withheld tax within ten days after month end, issue a prescribed certificate to the deductee, and face late fee and interest consequences for failures. Deductees claim electronic cash ledger credit as reflected in the deductor's return; refunds for excess or erroneous deduction follow the refund provisions, with no refund to a deductor where the amount is credited to the deductee's ledger.