Tax Deduction at Source obligations: failure to deduct or pay tax prevents deduction of related payments until tax is paid. Amendment makes amounts on which tax is deductible at source under Chapter XVII-B - including interest, royalty, technical fees, commission, brokerage, professional fees, and contractor payments - non-deductible if tax has not been deducted or, after deduction, not paid within the prescribed time, while restoring deduction in the year the tax is actually deducted or paid; it also excludes deduction for securities transaction tax, and defines relevant terms by reference to existing explanations in the Income-tax Act.