You are the tax accountant at Vertex Plant.
Vertex buys equipment for $5,000,000. Accounting depreciation: straight-line over 10 years. Tax depreciation: 40% / 30% / 20% / 10% over 4 years. Corporate tax rate is 25%. At the end of Year 1, the carrying amount is $4,500,000 and the tax base is $3,000,000.
Temporary difference = Carrying amount − Tax base (for an asset).