Da arrears calculation

1. Rule 21A deals with computation of relief u/s 89. There is no specific mention of how to bifurcate arrears salary. However, it's been specified as "salary relating to the PY". 
2. If proper bifurcation of salary is not available as per the employer documents, then it would be prudent to apportion the salary based on the number of months. 
3. In your case, if arrears are given for 14 months and PY relating to such arrears were specified then apportioning based on the number of months is the only option available. 
4. Yes, apportionment based on the number of months can be done. 
Please correct me if the above interpretation has an alternative view. 

OK Thank you.