Resignation Checklist- Task need to be assigned on last working day

Summary:

Resignation checklist is triggered 20 days before Last working day, there's a task(IT clearance) which needs to be allocated on Last working day.

Configurations set are: Days of initiation : -20
Delay duration(for IT clearance) : 20

When employee's resignation and Last working days is less than 20, the 'IT clearance' gets assigned after last working day.
So, is there a way to get the IT Clearance on last working day?

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