Though I agree with Shilpi Ma'am on first blush, I see a possible problem here.
Section 31 reads as under:
(2) A registered person supplying taxable services shall, before or after the provision of service but within a prescribed period, issue a tax invoice, showing the description, value, tax charged thereon and such other particulars as may be prescribed:
Rule 47 reads as under:
The invoice referred to in rule 46, in the case of the taxable supply of services, shall be issued within a period of thirty days from the date of the supply of service:
Provided that where the supplier of services is an insurer or a banking company or a financial institution, including a non-banking financial company, the period within which the invoice or any document in lieu thereof is to be issued shall be forty five days from the date of the supply of service:
Provided further that an insurer or a banking company or a financial institution, including a non-banking financial company, or a telecom operator, or any other class of supplier of services as may be notified by the Government on the recommendations of the Council, making taxable supplies of services between distinct persons as specified in section 25, may issue the invoice before or at the time such supplier records the same in his books of account or before the expiry of the quarter during which the supply was made.
Admittedly, the supplier has violated Rule 47 here. A question which arises here is whether Rule 47 is mandatory or directory provision? whether an invoice issued in violation of Rule 47 shall be treated as as invoice at all? In this context, the department can take a stand that Section 16(2)(a) is not satisfied here (Assuming all other conditions of section 16 is satisfied).
In such scenarios, the defense should be that It is not in the jurisdiction of the PO of recipient to adjudicate the compliance of Rule 47 by the supplier. However, one cannot rule out the possibility of litigation IMO.