Tax deduction at source on works contracts requires withholding, deposit, certificate issuance and adjustment against output tax. Section 36A requires persons other than individuals or HUFs who pay for transfer of property in goods under works contracts above the notified threshold to deduct tax at the specified rate at credit or payment; contractors must likewise deduct from sub-contractors. The Commissioner may certify that only part or none of a contract attracts deduction. Deducted amounts must be deposited into the Government treasury within the prescribed period and certificated to the contractor; such deposits count as tax paid and are adjustable against output tax. Non-compliance attracts penalties, interest, asset charge and requires obtaining a Tax Deduction Account Number.