Leave encashment wage type exemption/COA

Hi,

we have a custom wage type for leave encashment for one of the employe leave encashment amount reached 300000 limit so system considering 300000 as a leave encashment exemption but here we want remaining amount of leave encashment should be COA Basis.

Example : 1000000 is leave encashment

300000 is exemption amount

700000 is COA BASIS.

kindly suggest solution.