Rama Jois, J.

1. These are six connected writ appeals presented by the income-tax department against the judgment rendered by a single judge in W. Ps. Nos. 926 to 928 of 1972 and 3401 to 3403 of 1973, reported in M. Nagappa v. ITO [1975] 99 ITR 32 (Kar), declaring that sub-section (4) of s. 139 of the I. T. Act, 1961 (hereinafter referred to as " the Act"), to the extent it required a registered firm to pay interest at the rates specified, on the amount of tax though not payable by the registered firm but which would have been payable by it had it been assessed as an unregistered firm, if there was delay in fling the income-tax returns, as void as offending article 14 of the Constitution.

2. The respondents in all the appeals are registered firms, who are assessed to income-tax under the provisions of the Act. The assessment years, in the case of respondent in W. As. Nos. 427 to 429 of 1974, are 1965-66, 1966-67 and 1967-68, in the case of respondent in W. A. No. 426 of 1974 the assessment year is 2969-70, and in the case of the respondent in W. As. Nos. 424 and 425 of 1974 the assessment years are 1969-70 and 1970-71. There was some delay on their part to file the income-ta