Judgment :- P.A. Mohammed, J. The short question that arises for determination in this writ petition is whether the first respondent assessing authority is bound to disclose the materials for resorting to an assessment under S.6(2) of the Kerala Building Tax Act, 1991 (for short'the act). 2. S.6 deals with as to how the capital value of the building has to be determined for the purpose of the Act. The 'capital value' of a building means the value arrived at by multiplying the annual value of a building by ten as defined in clause (f) of S.2. Sub-s.(1) of S.6 prescribes that the annual value of a building shall be the annual value fixed for that building in the assessment books of the local authority within whose area the building is situate. Sub-s.(2) says that if the assessing authority is of opinion that the annual value fixed for a building in the assessment books of the local authority is too low, it may, after giving the person or persons affected thereby an opportunity of being heard. fix the annual value of the building. Thus, the power is conferred on the assessing authority to determine the annual value of a building notwithstanding the availability of its capitalised value on the basis of the assessment books of the local authority. But, this power can be exercised only when the assessing authority is of opinion that the annual value fixed in the assessment books is too low. This cannot be a mere ipse dixit of the assessing authority; it must be supported by cogent materials. In other words, there must be sufficient reasons to say that the annual value as per the assessment books is too low. 3. By Ext. P1, the petitioner has been assessed to the building tax at Rs. 28,500/ -. Ext. P1 contains Forms V and VI prescribed respectively under Rr. 8(1) and 9 of the Kerala Building Tax Rules, 1974. Form V is prescribed for the order of assessment and Form VI is for demand notice. The capital value of the building was assessed to Rs. 5,47,500/- as per the demand notice. No materials are disclosed for fixing the said capital value either in Form V or VI. The specific case of the assessee is that before determining the annual value of the building under sub s.(2) of S.6 no notice was issued to him. The capital value of the building was assessed to Rs. 5,47,500/- as per the demand notice. No materials are disclosed for fixing the said capital value either in Form V or VI. The specific case of the assessee is that before determining the annual value of the building under sub s.(2) of S.6 no notice was issued to him. His further case is that the materials in support of such annual value had not been disclosed to him at any stage of the proceeding. On this question, the appellate authority in Ext. P2 observed thus: "the taluk file reveals that several hearing notices, calling for the return, documents and explanation have been issued to the appellant and acknowledged as such by him". The question is whether the notices for hearing or the notices calling for return, documents, explanation etc. would operate as a substitute for issue of notice and disclosure of materials. The right available under sub-s.(2) of S.6 is paramount and it cannot be dispensed with by adopting circuitous courses. 4. In what manner, the re visional authority dealt with this aspect is sufficiently clear from the following observation contained in Ext. P3 order. "The main contention of the revision petitioner is that he was not informed about the details of the assessment and how it arrived at. He cited the judgment of the Honourable High Court reported in 1990 (1) KLT 869 in which the Hon. High Court has held that the assessee is entitled to know the details of the assessment. It is seen from the file that the basis for the assessment has been recorded in detail in it. However, the K.B.T. rules provided only for a notice of demand after assessment. The statutory prescribed form does not provide for giving details, of the assessment." What is evident from the above order is that the basis or reasons for assessment has been recorded in the file. That means there are materials for finding that the annual value as per the assessment books of the local authority is too low. Then it may be a case for estimating the annual value under sub s.(2) of S.6. 5. When a case squarely falls within the periphery of S.6(2) what are the requirements to be observed by the assessing authority? Then it may be a case for estimating the annual value under sub s.(2) of S.6. 5. When a case squarely falls within the periphery of S.6(2) what are the requirements to be observed by the assessing authority? Now let us see how sub-s.(2) is framed" "(2) Notwithstanding anything contained in sub-s.(1), if the assessing authority is of opinion that the annual value fixed for a building in the assessment books of the local authority is too low, it may, after giving the person or persons affected thereby an opportunity of being heard, fix the annual value of the building". From the above provision, it is crystalline that the affording of opportunity of being heard to the affected persons is an indispensable requirement to be complied with by the assessing authority before fixing the annual value on the basis of materials other than those available from the assessment books maintained by the local authority. The opportunity of being heard as provided under this provision is not an empty formality. It must be effective and meaningful. Without disclosing the materials available with assessing authority to the affected persons in advance by issuing a notice in that behalf, the entire process of personal hearing would become a futile exercise. The disclosure of materials at the time of personal hearing would not suffice. The affected person may not be able to counter those materials effectively when they are disclosed only during the hearing. Therefore, what is required is that a notice contained all materials for resorting to action under S.6(2) shall be issued to the affected persons and objections if any, called for. This is a requirement to be observed before affording an opportunity of being heard to the affected persons, as provided under the said provision. Indubitably such procedure has not been followed in this case. 6. It is apt to recall in this context what has been said by this Court in Karunakaran v. Tahsildar (1990 (1) KLT 869). "The mere fact mat certain exercises had been made in the files kept in the office would be no consolation for the affected person. On the other hand, a citizen is certainly bound to discharge his liability cast under a valid assessment order. However, he must know the details on which an assessment has been made and the liability imposed. An assessment without the authority of law is unconstitutional. On the other hand, a citizen is certainly bound to discharge his liability cast under a valid assessment order. However, he must know the details on which an assessment has been made and the liability imposed. An assessment without the authority of law is unconstitutional. The decision will no doubt extend support to the view that I have taken herein above. 7. In view of what is said above, the respondents have committed an error in understanding the actual scope of sub-s.(2) of S.6. The impugned orders are therefore, liable to be set aside. Accordingly, Exts. P1 to P3 are quashed. 8. However, I direct the first respondent to complete the assessment afresh after issuing a notice containing the materials for determination of annual value of the building under sub-s.(2) of S.6 and after granting an opportunity of being heard to the petitioner. The petitioner is free to raise all his objections to the said notice as and when issued. The original petition is allowed as above.