Cost Basis

Cost basis for what ???  Be much more specific. 

For the purposes of depreciation, the cost basis of real estate property is the *LOWER* of what you actually paid for it, or it's FMV on the date it was placed in service.

For non-real estate property, such as equipment used to produce income in a business, the cost basis is the *LOWER* of what you paid for it, or it's FMV on the date you placed it in service.

If you are trying to determine cost basis for the purpose of reporting the sale of an asset, then it depends on exactly what that asset is and weather or not you used the original purchase price for depreciation.

Cost-basis can also be different for intangible non-material assets, such as goodwill.