Dear Sir,
The Honble Allahabad High Court had held that even thogh declaration form for claiming exemption/concession may be required to be filed during the course of assessment proceedings but, in cases of non furnishing thereof, tax has to be levied at the normal rate which would become the admitted tax and interest and would be liable from the due date of the return in which turnover was disclosed and exemption/concession has been claimed. There is no scope for consideration of legitimate expectation or hope or bonafide pleas of the Act - CIT vs Control Switch Gears Co. Ltd. (2011) 10 VSTI 18 (All).
Further, you can also go through the case law 'J.K.Synthetics Ltd. vs. CTO (1994) 94 STC (SC) In this matter the Hon'ble Supreme Court had laid down cerntain principles regarding where the dealer has paid tax bonafidely but the amount of tax is enhanced at the time fo assessment, which may be useful in deciding the above issue in hand.
Best Regards,
Pradeep Khatri