Sh.Gupta Ji,
It is Section 16(4) and not (15) as per revised MGL. I understand as under:-
ITC is not permitted on the strength of "any invoice or debit note" after furnishing of the return for September or Annual return which ever is earlier"
Here 'any invoice' includes supplementary invoice or any other document which conform to the definition of 'Invoice', (by whatever name called) or debit note.Credit is not allowed on the strength of those invoices or debit notes which relate to the original invoices issued previous financial year. Balance Sheet is to be prepared by 30th September every year and annual return is prepared on the basis of Balance Sheet. Both are to be filed by stipulated dates. Normally monthly return is filed first and annual return is filed thereafter.
The purpose is not to allow credit on the above docs after finalisation of return for September or annual return.