What is the time limit to avail Input Tax Credit. (ITC) ?

Section 16(4) of CGST Act, 2017

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.