The assessee, a tax resident of Canada, received consideration for supplying reservoir simulation software to Indian oil companies, on which tax was deducted at source. The Assessing Officer assessed the receipts under section 44BB. The Tribunal held that since the assessee had no permanent establishment in India, it was entitled to the more beneficial provisions of the India-Canada DTAA under section 90. Consequently, the receipts were not taxable as business income under section 44BB. It was further held that where the entire income of a non-resident is subject to tax deduction at source, there is no liability to pay advance tax and, therefore, interest under section 234B could not be levied. The Assessing Officer was also directed to grant due credit for TDS and interest under section 244A. (AY.  2012-13, 2019-20 to 2021-22)