Most people who sell assets are familiar with the income tax concept of "basis." Basis, in its simplest form, is essentially what you pay for something. When you sell an asset, you're not taxed on the sales proceeds. Instead, you pay tax on the difference between your net sales proceeds and your cost basis. Net sales proceeds is equal to gross sales proceeds reduced by any selling expenses. Cost basis is equal to purchase price plus increases to the purchase price less accumulated depreciation or amortization. Basis, therefore, reduces the amount of otherwise taxable gain.
The concept of "basis" also applies to traditional IRA's. When you make a contribution to a traditional IRA, your contribution is either deductible, partially deductible, or nondeductible depending upon (1) whether you're an active participant in a qualified retirement plan, (2) the amount of your modified adjusted gross income, and (3) your tax filing status. To the extent that any portion of your IRA contributions are deductible, they aren't credited with any basis. Nondeductible IRA contributions, on the other hand, are counted as, and increase, traditional IRA basis.