Section 31(7), Arbitration and Conciliation Act, 1996
(a) Unless otherwise agreed by the parties, where and in so far as an arbitral award is for the payment of money, the arbitral tribunal may include in the sum for which the award is made interest, at such rate as it deems reasonable, on the whole or any part of the money, for the whole or any part of the period between the date on which the cause of action arose and the date on which the award is made.
(b) A sum directed to be paid by an arbitral award shall, unless the award otherwise directs, carry interest at the rate of eighteen percentum per annum from the date of the award to the date of payment.
(1) Where and in so far as a decree is for the payment of money, the Court may, in the decree, order interest at such rate as the Court deems reasonable to be paid on the principal sum adjudged, from the date of the suit to the date of the decree, in addition to any interest adjudged on such principal sum for any period prior to the institution of the suit, with further interest at such rate not exceeding six per cent per annum as the Court deems reasonable on such principal sum, from the date of the decree to the date of payment, or to such earlier date as the Court thinks fit:
Provided that where the liability in relation to the sum so adjudged had arisen out of a commercial transaction, the rate of such further interest may exceed six per cent, per annum, but shall not exceed the contractual rate of interest or where there is no contractual rate, the rate at which moneys are lent or advanced by nationalised banks in relation to commercial transactions.
Explanation I-- In this sub-section, "nationalised bank" means a corresponding new bank as defined in the Banking Companies (Acquisition and Transfer of Undertakings) Act, 1970 (5 of 1970).
Explanation II-- For the purposes of this section, a transaction is a commercial transaction, if it is connected with the industry, trade or business of the party incurring the liability.
(2) Where such a decree is silent with respect to the payment of further interest on such principal sum from the date of the decree to the date of payment or other earlier date, the Court shall be deemed to have refused such interest, and a separate suit therefor shall not lie.