Salary Arrear Query

Good Morning Sir
 client is working in muncipal corporation last year FY 22-23 he has told me that he received arrears of 7th pay commission and provided me arrear sheet, i considered total arrear amount provided in sheet and calulated relief accordingly ( in that arrear sheet total arrear amount provided but total arrear was not received in FY 22-23  it was getting paid in EMIS) and filed return last year ,now this year  he has received one emi of arrear in FY 23-24 which is included this years for 16 salary.
How i can correct this mistake
and what implecations are there please guide