Income Tax Basis - (1) For tax purposes, concept of basis determines proper amount of gain to report when an ASSET is sold. Basis is usually the cost paid for an asset plus amounts paid to improve the asset less deductions taken against asset, like AMORTIZATION andDEPRECIATION. (2) For accounting purposes, a consistent basis of accounting which uses income tax accounting rules whereas GENERALLY ACCEPTED ACCOUNTING PRINCIPLES (GAAP) doesn't.