Even if you can use Form 1040EZ, it may benefit you to use Form 1040A or 1040 instead. For example, you can claim the head of household filing status (which usually results in a lower tax than single) only on Form 1040A or 1040. You can claim the retirement savings contributions credit (saver's credit) only on Form 1040A or 1040. Use TeleTax topic 610 (see page 26).
If you paid state or local real estate taxes or purchased a new vehicle after February 16, 2009, you may qualify for an increased standard deduction only if you file Form 1040A or 1040. Similarly, if you suffered personal casualty losses from a federally declared disaster, you may qualify for the increased standard deduction if you file Form 1040. Use TeleTax topic 551 (see page 26) or the Instructions for Schedule L (Form 1040A or 1040). taxmap/instr/i1040ez-010.htm#TXMP7502ff6e
You can itemize deductions only on Form 1040. You would benefit by itemizing if your itemized deductions total more than your standard deduction: $5,700 for most single people; $11,400 for most married people filing a joint return. Use TeleTax topic 501 (see page 26). But if someone can claim you (or your spouse if married) as a dependent, your standard deduction is the amount on line E of the worksheet on the back of Form 1040EZ.