For income tax purposes, the original cost or other original basis, adjusted for such things as casualty losses, improvements, and depreciation, when appropriate. The basis is increased by capital improvements and decreased by depreciation deductions. After these adjustments, the property then has an 'adjusted basis.'
After a taxpayer's basis in property is determined, it must be adjusted upward to include any additions of capital to the property and reduced by any returns of capital to the taxpayer. Additions might include improvements to the property and subtractions may include depreciation or depletion. A taxpayer's adjusted basis in property is deducted from the amount realized to find the gain or loss on sale or disposition.