Telegraphic transfer buying rate governs exchange rate for TDS on income payable in foreign currency on the deduction date. For deduction of tax at source on income payable in foreign currency, the rate of exchange for calculating value in rupees shall be the telegraphic transfer buying rate of such currency as on the date tax is required to be deducted. This applies to payments to an assessee outside India, to a Unit located in an International Financial Services Centre, and by such a Unit to an assessee in India. 'Telegraphic transfer buying rate' is the rate adopted by the designated bank for buying the currency having regard to guidelines by the monetary authority where currency is made available through telegraphic transfer.