Order of permanent alimony under Section 25 of Hindu Marriage Act, 1955 can be varied, modified or rescinded: 

I. if the party in whose favor the order has been passed, remarries 

II. if the party in whose favor the order has been passed, if the wife, and she has not remained chaste. 

III. if the party in whose favor the order has been passed is the husband and he has had sexual intercourse with any other woman.