For instance, let's assume that a company purchased a building 30 years ago at a cost of $600,000. The company then depreciated the building at a rate of $20,000 per year for 30 years. Today the building continues to be used by the company and it plans to continue using it for many more years. The company's current balance sheet will report the building at its cost of $600,000 minus its accumulated depreciation of $600,000. In other words, the building will be reported at its book value of $0.
The cost principle prevents the company from recording and reporting more than its actual cost of $600,000. The matching principle requires that only the actual cost of $600,000 can be allocated or matched to the years in which the company benefits from the use of the building. Lastly, the company is assumed to be a going concern and therefore it is not liquidating. Hence the amount that the company would receive if it sold the building is not appropriate for its financial statements.
Even if the building's current value is estimated to be $2 million, the financial statements must report the actual cost and the depreciation based on that cost—even if this means reporting a book value of $0. It also means there will be no additional depreciation expense reported after the $600,000 of actual cost has been reported as depreciation expense.