Tax deduction at source required from notified government payers for high-value supplies, with credit and interest consequences. Section 51 authorises the Government to mandate specified public entities to deduct tax at the rate of one percent from payments to suppliers under high-value contracts, excluding tax components shown on the invoice and except where supplier location and place of supply differ from recipient registration. Deductors must remit deductions within ten days after month end and issue prescribed certificates; failure to furnish certificates incurs a late fee. Deductees claim credit in the electronic cash ledger as per the deductor's return; interest applies for non-payment and refunds follow the Act's refund provisions, with no deductor refund if credited to the deductee.