The Internal Revenue Service tax tables for the 1040a form can be found on the official IRS website, as of 2015. The website also contains many other helpful resources for taxpayers.
From the Internal Revenue Service main page, click on "Tax Table" under the Forms & Pubs section. Depending on your browser settings, the page opens in a new browser window or a dialog box appears for you to save the file on the hard drive of your computer.
The IRS tax tables are used to calculate the amount of taxes that are owed based on taxable income for the year.