Dimunition in value of investment

Dear All,

Whether dimunition in value of investment is timing or permanent difference?

E.g. Suppose, if a company has belief that its long terms investment of Rs. 1 crores are decling and it creates provision for dimunition of Rs. say 10 lacs in books of accounts. However in income tax no deduction is allowed. Whether it is timing or permenent difference as per AS22.

Regards

Shweta Maheshwari