Dear Friend,
Your question raiese another question, are you from HR?
You are paying higher HRA on the basis of location of the posting. When such employee proceeds on leave and visits his home town where HRA is comparatively lower, you can not reduce the HRA.
You can only reduce the HRA if he is transferred to another location having low HRA.
To be judicious you can not reduce if place of posting has not changed. The thought also is not justified.
Warm Regards
Bharat Gera
HR Consultant
9322404765