You can calculate the OROP arrears in the following way:
1. Find the Basic pension as per OROP chart- table. say for Example; Hav and equal Ranks- Sgt- Group- X QS:15 yrs.
|As per Table no: 7 of OROP Tables||8585|
|As per Cir 501,table No.17||6374
|Difference per month||2211|
Now the Effective Date is From 01-07-2014
Arrears from 1-7-2014 to 31-01-2016 will be-Difference X a factor of 40.53 , 2211 X 40.53 = 89612/-
SO- 89612 IS THE ARREARS
This will be paid in 4 equal half yearly installments.
For family pensioners, in one installment.
This the simple way of calculation.
Also Read:Lok Sabha Q & A committee on allowances of 7th CPC