Sh.Mukund Thakkar Ji,
Sir, Different view is always for the betterment. It should be welcomed. It opens closed mind. Dissent can thaw(melt) frozen thinking in countless ways. (It is a quote).
Section 50(3) of CGST Act talks of Section 42 (10) & Section 43 (10).
"A taxable person who makes an undue or excess claim of input tax credit under sub-section (10) of section 42or undue or excess reduction in output tax liability under sub-section (10) of Section 43, shall pay interest on such undue or excess claim or on such undue or excess reduction, as the case may be, at such rate not exceeding twenty-four per cent., as may be notified by the Government on the recommendations of the Council."
"Section 42(10) The amount reduced from the output tax liability in contravention of the provisions of sub-section (7) shall be added to the output tax liability of the recipient in his return for the month in which such contravention takes place and such recipient shall be liable to pay interest on the amount so added at the rate specified insub-section (3) of section 50."
"Section 43 (10) The amount reduced from output tax liability in contravention of the provisions of sub-section (7) shall be added to the output tax liability of the supplier in his return for the month in which such contravention takes place and such supplier shall be liable to pay interest on the amount so added at the rate specified in sub-section (3) of section 50."
If we peruse all above in tandem, it makes clear that interest is chargeable only if credit is used. The department cannot go beyond the scope of GST law.
There are case laws to this effect.