JUDGMENT A. K. PATNAIK, J. - Heard Mr. C. R. Dey, Mr. Chopra and Mr. S. K. Singh, learned counsel for the petitioners. Mr. U. B. Saha, learned Government Advocate, State of Tripura, was heard on September 9, 1998. Mr. B. Sarma states that Mr. U. B. Saha will only be available before this Bench on October 22, 1998. Since the civil rule is required to be disposed of expeditiously, no further adjournment can be allowed up to October 22, 1998 as prayed for on behalf of Mr. U. B. Saha. 2. The case of the petitioners in this writ petition is that they own a small-scale industrial unit located at Silchar in the district of Cachar, Assam, and are manufacturing stone chips, etc., in the said industrial unit. The said industrial unit is a dealer registered under the Assam General Sales Tax Act, 1993. It is also registered under the Central Sales Tax Act, 1956. It has been supplying stone chips and other goods to different parties in the State of Tripura for the last several years. Pursuant to tender notice, the petitioners have been awarded three different contracts for supply and stacking of stone chips to the project sites of respondents Nos. 6 to 10 in the State of Tripura. Pursuant to the said contracts, the petitioners are now to transport the stone chips to the project sites of respondents Nos. 6 to 10 in the State of Tripura. According to the petitioners, the sales under the said three contracts to the respondents Nos. 6 to 10 are inter-State sales liable to sales tax under the Central Sales Tax Act, 1956 and such sales tax is payable to the Central sales tax authorities in the State of Assam. However, for transporting the stone chips to the project sites of respondents Nos. 6 to 10 in the State of Tripura, they required form No. XVIII as prescribed by rule 46 of the Tripura Sales Tax Rules, 1976. Accordingly the petitioners requested the Boarder Road Task Force to obtain form No. XVIII from the Superintendent of Taxes, Government of Tripura and send the same to the petitioners so that stone chips can be transported to the project sites in the State of Tripura. Accordingly the petitioners requested the Boarder Road Task Force to obtain form No. XVIII from the Superintendent of Taxes, Government of Tripura and send the same to the petitioners so that stone chips can be transported to the project sites in the State of Tripura. By order dated June 1, 1998 passed by the Superintendent of Taxes, Government of Tripura, the Boarder Road Task Force was informed that since the petitioners are not registered dealers under the Tripura Sales Tax Act and Rules they are not entitled to get form until the petitioners get themselves registered as registered dealers under the said Act and Rules. Aggrieved by the said order dated June 1, 1998 of the Superintendent of Taxes, the petitioners have moved this Court for appropriate relief under article 226 of the Constitution. 3. Mr. C. R. Dey and Mr. V. K. Chopra, learned counsel for the petitioners, vehemently contended that the sale transactions in favour of the respondents Nos. 6 to 10 are all inter-State sales and that respondents Nos. 6 to 10 are the consignee of the goods in question and therefore the petitioners Were not selling the said goods inside the State of Tripura. They further pointed out that under the Tripura Sales Tax Act 1976 registration is only required for selling goods inside the State of Tripura. According to the petitioners, the insistence on the part of the Superintendent of Taxes, Government of Tripura, for registration of the petitioners as a registered dealers under the Tripura Sales Tax Act and Rules made thereunder is illegal. They further pointed out that even on previous occasions the petitioners have supplied stone chips to various project sites inside the State of Tripura and have been issued with form No. XVIII by the authorities under the Tripura Sales Tax Act and Rules made thereunder. They referred to the copy of the forms which has been annexed to the writ petition as annexure 6. According to Mr. Dey and Mr. Chopra, the sales tax authorities of the, State of Tripura were therefore estopped from taking a stand that the sale in question was sale inside the State of Tripura and that the petitioners have to be registered under the Tripura Sales Tax Act and Rules made thereunder before form No. XVIII are issued for transportation of the goods to the project sites in the State of Tripura. 4. Mr. 4. Mr. U. B. Saha, learned Government Advocate, however, appeared on September 9, 1998 and submitted that according to the sales tax authorities of the State of Tripura, the proposed sale in question to respondents Nos. 6 to 10 is a sale inside the State of Tripura and that the petitioners were self-consignee of the goods in question. He referred to the provisions of sections 2(b), 37 and 38 of the Tripura Sales Tax Act, 1976 to show that once a dealer sells goods inside the State of Tripura, he is liable to register himself under the said Act and Rules made thereunder. He also referred to rules 46 and 47 of the Tripura Sales Tax Rules, 1976 to show that unless a dealer is registered under the Tripura Sales Tax Act, 1976, he is not entitled to form No. XVIII. 5. The question as to whether the supply of the stone chips by the petitioners to respondents Nos. 6 to 10 under the three different contracts is an intra-State sale from Assam to Tripura liable to tax under the Central Sales Tax Act or is an inter-State sale in the State of Tripura is a mixed question of fact and law and such a question cannot be decided by this Court under article 226 of the Constitution. Further as to whether the petitioners are at all liable for the sales tax on the goods under the Tripura Sales Tax Act, 1976 cannot be decided by this Court under article 226 of the Constitution at this stage without any assessment process as such being initiated or completed against the petitioners under the said Act. It is only in an assessment proceeding initiated under the Tripura Sales Tax Act, 1976 that the question as to whether the petitioners are liable to sales tax under the Tripura Sales Tax Act, 1976 can be decided and not otherwise. Similarly the question as to whether the sale of the goods by the petitioners to the respondents Nos. 6 to 10 is an inter-State sale from Assam to Tripura is a question which can only be decided by the Central sales tax authorities in the State of Assam and not by this Court under article 226 of the Constitution at this stage when no assessment proceeding had been initiated under the said Act by the Central sales tax authorities in the State of Assam. 6. 6. As a matter of fact in this writ petition no assessment either under the Tripura Sales Tax Act, 1976 or under the Central Sales Tax Act, 1956, has been challenged and all that has been challenged is the order dated June 1, 1998 of the Superintendent of Taxes, Government of Tripura by which it has been held that since the petitioners are not registered dealers under the Tripura Sales Tax Act and Rules they are not entitled to get statutory form No. XVIII until they get themselves registered under the said Act and Rules. Form No. XVIII is issued under rule 46 of the Tripura Sales Tax Rules, 1976. A bare reading of rule 46 would show that it is only a registered dealer who can be issued with form No. XVIII. Thus until and unless the petitioner is a registered dealer under the Tripura Sales Tax Act, 1976, the petitioner cannot be furnished with form No. XVIII. It appears that the petitioner on previous occasions was issued with form No. XVIII even though it was not a registered dealer. But then there is no estoppel against law and in any case estoppel does not apply to taxation law. If the rule 46 provides that it is only the registered dealer who can be issued with form No. XVIII then it is only a registered dealer who can be issued such form No. XVIII notwithstanding the fact that on earlier occasions the petitioners though not registered dealers were issued form No. XVIII. 7. The real apprehension of the petitioners is that in case they apply for registration under the Tripura Sales Tax Act, 1976 and are registered dealer under the said Act, the authorities may take such conduct on the part of the petitioners to be proof of the fact that the petitioners are selling goods inside the State of Tripura. As has been held above, the question as to whether the petitioners are in fact selling goods in the State of Tripura is a mixed question of fact and law and will be decided only in the assessment proceeding and not otherwise and the fact that the petitioners have applied for registration and have been issued with registration certificate under the Tripura Sales Tax Act, 1976, will not make the petitioners liable to sales tax on the transanction in question under the said Act. 8. 8. For the aforesaid reasons, I dispose of this writ petition with a direction that in case the petitioners apply for registration under the Tripura Sales Tax Act, 1976 and are granted registration certificate and on the strength of the said registration certificate the petitioners apply for form No. XVIII and are granted the same for transportation of the goods to the project sites of the respondents Nos. 6 to 10 under the three contracts in question, such conduct of the petitioners will not make them liable to sales tax under the Tripura Sales Tax Act, 1976 and that the question as to whether or not they will be liable under the said Act for tax will only be decided in an appropriate proceeding for assessment if any initiated against the petitioners under the said Act and Rules and not otherwise. Ordered accordingly.