Sir,
Rule 87(6) states that Challan Identification(CIN) Number is generated upon successful credit of amount to the concerned account maintained with the authorised Bank.
GST is collected through "e-kuber", Core Banking System of RBI. The CIN details details are consolidated by e kuber several times in a day and the fund is credited to respective Government Account, as per document titled "RBI e-kuber GST Receipts and memorandum of error, Technical Specification for Government Integration v1.4.1" released by RBI.
Once the money is taken out from account of the tax payer and put into the Consolidated Fund of India / State, nothing remains to be transferred. It is receipt of money in the hads of the exchequer.
Once is money is received by the Government, it cannot be said that the tax payer has not made the payment by any stretch of imagination.
Once the money is available to the Government for enjoyment, there is no deprival.
Interest can at best run from due date till date of challan. Any attempt to levy interest from date of challan till filing of return appears to be illegal and illogical.
Further, till the manner of calculation of interest is prescribed as required under section 50(2), demand of interest does not have the authority of law. When a levy can not be measured, it cannot be collected by adopting any manner of calculation of interest at the sweet will and volition of authorities.