Learn about the 1040a tax form. http://americantaxservice.org/the-irs-form-1040a-explained/ orm 1040A is one of the forms that can be used when filing federal taxes in the US. This form is shorter than the original 1040 form; however, it is more complex than the 1040EZ form. All taxpayers can use form 1040, yet there are restrictions as to which taxpayers can use Form 1040A.