A.K. JAYASANKARAN NAMBIAR, J.

1. The issues involved in these three writ petitions being similar, they are taken up together for consideration and disposed by this common judgment. The petitioners in the writ petitions, who are conducting business in Granite Metals, are assessees under the Kerala Value Added Tax Act (hereinafter referred to as the KVAT Act). As per the provisions of Section 8(b) of the KVAT Act, any dealer producing granite metals with the aid of mechanized crushing machines may, at his option, instead of paying tax as per the regular mode of assessment under the KVAT Act, pay tax at the compounded rate envisaged under that Section. The compounding provision, as it stood in the Assessment Year 2008-09, reads as follows:-

8. Payment of tax at compounded rates:-

Notwithstanding anything contained in Section 6 –

(a)...................................

(b) Any dealer producing granite metals with the aid of mechanized crushing machine may, at his option, instead of paying tax in accordance with the provisions of the said sections, pay tax at the following rates, namely:-

(ii) For the each crushing machine of size exceeding 30.48 cm x 22.86 cm but not exceeding –

(a) For each crushing machine of size not exceeding 30.48 cm x 22.86 cm = Rs. 50,000 per annum. 40.64 cm and 25.40 cm = Rs. 1,60,000 per annum.

(iii) For the each crushing machine of size exceeding 40.64 cm x 25.40 cm = Rs. 3,20,000 per annum.

(iv) For each cone crusher Rs. 7,50,000 per annum.

Provided that in the case of dealers, who opted to pay compounded tax under this clause, no separate assessment shall be made in respect of m-sand produced by them.

Explanation – For the purposes of this clause, primary crusher shall also be reckoned for the purpose of computation of the quantum of compounded tax and the rate applicable for primary crusher shall be fifty per cent of the rates mentioned in items (i), (ii) and (iii) above."

By the Finance Bill 2009, the said provision was amended by inserting the following proviso, after the existing proviso under Section 8(b)(iv), as follows:-

"Provided further that dealers with a single crusher other than cone crusher shall pay rupees twenty-five thousand only per annum as tax under this clause."

This amendment through the Kerala Finance Bill 2009, was made effective from 1st April 2009 and the collection of tax on the basis of the said provisions was authorised through a declaration made in terms of the Kerala Provisional Collection of Revenues Act, 1985. Thereafter, when the Kerala Finance Act 2009 came into force, the proviso was amended to read as follows:-

"Provided further that notwithstanding anything contained in this clause, dealers with a single crushing machine of size not exceeding 30.48 cm x 22.86 cm. shall pay rupees twenty five thousand only per annum as tax under this clause."

Explanation – For the purpose of this clause, primary crushers shall also be reckoned for the purpose of computation of compounded tax, and the rate applicable to primary crushers shall be at fifty per cent of the aggregate of the tax payable on secondary crushers.

2. The petitioners in the above writ petitions opted for payment of tax at the compounded rate, as envisaged in Section 8(b) of the KVAT Act, under the belief that the rate applicable to them, insofar as they owned only a single crushing machine, would be only an amount of Rs. 25,000/- which was the figure indicated in the proviso to Section 8(b) (iv) of the KVAT Act at the time when they were called upon to exercise their option. The applications preferred by the petitioners, opting to pay tax at compounded rate, were on this assumption regarding the amount to be paid. In the case of the petitioner in W.P. (C) No. 18043 of 2010, Ext.P1 is the permission dated 08.07.2009, given to the petitioner by the first respondent, to pay tax at the compounded rate for an amount of Rs. 25,000/- as envisaged in the proviso as it then stood. It is seen from Ext.P1 permission