When it comes to taxes, simple is better. Finding the simplest forms for your situation are advisable, because making a mistake that could cost you a delay in processing your taxes and any due refunds. The Federal Tax Return Preparation form that is the simplest is 1040EZ. Form 1040A has additional items not covered in the EZ. Use Form 1040 when you itemize deductions and report complicated investments and other income. Note: The income limit for Forms 1040EZ and 1040A has increased to taxable income of less than $100,000.