Assessee-firm is  a Government approved civil contractor and was engaged in 100 per cent Government contracts only. Revenue estimated income of assessee at certain amount and while doing so interest on FDR, interest on NSC and interest on income tax refund were excluded for purposes of estimations holding such income to be unconnected to contract business per se. On appeal the Tribunal held that interest on FDRs could not be seen differently from receipt derived directly from contract work. Having regard to nature of business, FDRs were integral part of working capital of assessee kept and expanded for commercial reasons. Fixed deposits were a necessity to provide security and meet contingency of such peculiar business. Therefore, interest income earned on fixed deposits deserved to be treated alike with business contract receipts for purposes of estimations and it could not be treated differently from contract receipts merely because such income flowed from a different source. However, interest income on IT refunds and NSC deposits would not get benefit of estimations but would be chargeable as other income in accordance with law. (AY. 2015-16 to 2020-21)