GST IS NOT TAKEN INPUT TAX

DEAR SIR

MY COMPANY IS SALE OF THE GOODS ONE CUSTOMER, MY COMPANY SALE BILL PREPARED FOR THE MONTH OF MAY-2021, FILING THE GSTR-1, BUT CUSTOMER IS NOT TAKEN INPUT TAX CREADIT FOR THE MONTH OF MAY-2021, CUSTOMER IS PAID FULL AMOUNT FOR THE MONTH OF MAY-2021.

MY DOUT IS HOW TO TAKEN INPUT TAX CREADIT OF MY CUSTOMER.

PLEASE CLARIFIED MY PROBLEM.

THANKING YOU

G.O.REDDY