S. 234B interest is automatic if conditions are met. Form I.T.N.S. 150 is a part of the assessment order and it is sufficient if the levy of interest is stated there

CIT vs. Bhagat Construction Co. Pvt. Ltd (Supreme Court)

It will be seen that under the provisions of Section 234B, the moment an assessee who is liable to pay advance tax has failed to pay such tax or where the advance tax paid by such an assessee is less than 90 per cent of the assessed tax, the assessee becomes liable to pay simple interest at the rate of one per cent for every month or part of the month. The levy of such interest is automatic when the conditions of Section 234B are met. The facts of the present case are squarely covered by the decision contained in Kalyankumar Ray’s case inasmuch as it is undisputed that contained a calculation of interest payable on the tax assessed. This being the case, it is clear that as per the said judgment, this Form must be treated as part of the assessment order in the wider sense in which the expression has to be understood in the context of Section 143, which is referred to in Explanation 1 to Section 234B