When it comes time to file taxes for 2005, it all boils down to just three essential federal tax forms: the 1040EZ, the 1040A, and the 1040. The IRS recommends using the simplest form you qualify for to reduce the likelihood of errors that could result in you paying higher taxes or a delay when you file taxes. While each of the federal tax forms has its own criteria for use, the 1040EZ is usually appropriate for people who don't claim dependents and have taxable income below $100,000. The 1040A is used most often by people with dependents and more than $100,000 in taxable income. And the 1040 is suited to those with more than $100,000 in taxable income or anyone who wishes to itemize deductions rather than take the standard deduction.