1.“Not Sure” lets the software choose what you qualify for and is recommended unless you know which tax form you qualify for under IRS Rules.
2. 1040EZ is the easiest, quickest and most widely commonly used but there are restrictions: Generally, you cannot earn more than $100,000 dollars in 2016; all your income must be from a W-2 form(s), Interest, Unemployment, or Alaska Dividend; and you must be single or married filing jointly.
3. 1040A is generally for taxpayers who have dependents. You may have income from almost any source and you may have any filing status.
4. 1040 is for all taxpayers no matter what your income level, source of income, and filing status. Anyone can use this form.