audit

Check the additions made during the year under the plant and machinery block. Ensure that only eligible plant and machinery is considered for additional depreciation. Please refer IT act for the same.

If it is a manufacturing concern, additional depreciation will be claimed on plant and machinery ( i.e., 20%). And important thing is whether plant and machinery is purchased before 182 days or after  182 days in a year. If it is more than 182 days 50% of the rate ( i.e., 50% of 20%) and otherwise normal rate.

See once section 32 of Income Tax Act 1961

@ ^^^^^^

and i think it is 180 days concept, not 182 days

Anand is right.It is 180 days concept.182 days is the concept of Residential Status.