What is the last date to claim Input Tax Credit under GST for FY 2017-18 ?

As per Section 16(4) of CGST Act 2017. Eligibility and conditions for taking input tax credit.

A registered person shall not be entitled to take input tax credit in respect of any invoice or debit note for supply of goods or services or both

• after the due date of furnishing of the return under section 39 for the month of September following the end of financial year to which such invoice or invoice relating to such debit note pertains or
• furnishing of the relevant annual return,whichever is earlier.

Every registered person, other than an Input Service Distributor or a non-resident taxable person or a person paying tax under the provisions of section 10 or section 51 or section 52 shall, for every calendar month or part thereof, furnish, in such form and manner as may be prescribed[ Rule 61 of CGST Rules],a return, electronically, of inward and outward supplies of goods or services or both, input tax credit availed, tax payable, tax paid and such other particulars as may be prescribed, on or before the twentieth day of the month succeeding such calendar month or part thereof

Where the time limit for furnishing of details in FORM GSTR-1 under section 37 and in FORM GSTR-2 under section 38 has been extended and the circumstances so warrant, the Commissioner may, by notification,  specify the manner and conditions subject to which the  return shall be furnished in FORM GSTR-3B electronically through the common portal, either directly or through a Facilitation Centre notified by the Commissioner.