Are there any relaxations available for banking companies or a financial institutions including NBFC

Yes. In case of the supplier being a Banking Company or a Financial Institution
including NBFC or an insurer, the tax invoice would be treated as complete if it contains other information in terms of Rule 46 of CGST Rules, even in the following cases:
 The invoice is not serially numbered;
 The invoice does not contain the address of the recipient of taxable supply.
Also, they may issue an invoice within 45 days from the date of supply of service (as against 30 days in other cases).

(ICAI FAQ PUBLICATIONS 06-09-2017 TAX INVOICE, CREDIT AND DEBIT NOTES: FAQ NO. 35)