You cannot claim a deduction for a depreciating asset’s decline in value if you are allowed a capital works deduction for the asset.
Capital works deductions may be available for expenditure on the construction of buildings and structural improvements and extensions, alterations or improvements to either of those.
Capital works deductions are not available for expenditure on plant.
Decline in value deductions may be available if your plant is a depreciating asset.
If your depreciating asset is not plant and it is fixed to, or otherwise part of, a building or structural improvement, your expenditure will generally be construction expenditure for capital works and only a capital works deduction may be available.
(For more information, see Deduction for decline in value of depreciating assets and Capital works deductions.)