IT0015 Allowance WT - Need assistance in Payroll calculation

Dear SAP Team,

I would need your advice on the below scenario and how to handle this:

If an employee completes 6 months of service, he is eligible for an allowance in his 7th month payroll. The actual earning for the last 6 months (only basic salary taken into consideration and not any other wagetypes. Also retro changes to be considered for Basic salary) divide by 6 would be his allowance.

For eg: His basic salary is 1000 (Jan-June). In March, he was on LOP for half month. Hence, his actual earning for 6 months is 5500/6=916.66 is the allowance paid in July Payroll.

Please let me know the best possible way to handle this.

Thanks!

Swetha