In accounting, book value or carrying value is the value of an asset according to its balance sheet account balance. For assets, the value is based on the original cost of the asset less any depreciation, amortization or Impairment costs made against the asset. Traditionally, a company's book value is its total assets minus intangible assets and liabilities. However, in practice, depending on the source of the calculation, book value may variably include goodwill, intangible assets, or both. When intangible assets and goodwill are explicitly excluded, the metric is often specified to be "tangible book value".

In the United Kingdom, the term net asset value may refer to the book value of a company.

An Asset's initial book value is its actual cash value or its acquisition cost. Cash assets are recorded or "booked" at actual cash value. Assets such as buildings, land and equipment are valued based on their acquisition cost, which includes the actual cash cost of the asset plus certain costs tied to the purchase of the asset, such as broker fees. Not all purchased items are recorded as assets; incidental supplies are recorded as expenses. Some assets might be recorded as current expenses for tax purposes. An example of this is assets purchased and expensed under Section 179 of the US tax code.^{[citation needed]}