you need to obtain permission of department before sale of any immovable properties
The Central Civil Services (Conduct) Rules, 1964
18. MOVABLE, IMMOVABLE AND VALUABLE PROPERTY:
No Government servant shall, except with the previous knowledge of the prescribed authority, acquire or dispose of any immovable property by lease, mortgage, purchase, sale, gift or otherwise either in his own name or in the name of any member of his family:
Provided that the previous sanction of the prescribed authority shall be obtained by the Government servant if any such transaction is with a person having official dealings with him.
3) if you fail to disclose sale of property disciplinary action can be taken against you