Tax books. Records kept by a firm's management that follow IRS rules. The books follow Financial Accounting Standards Board rules.

Each state's laws regarding sales tax are a little different, but in general any “tangible personal property” is considered taxable. This includes physical books. And, increasingly, states are also requiring sales tax digital books. Sales tax rates also vary across states, counties, cities and other local areas.

The tax-adjusted basis is calculated by taking the original cost or other basis of the asset in question and adjusting it for various tax-related allowances such as depreciation. Book-adjusted basis is a measure of what an asset is worth from a company's perspective on its books.