SITUATION #1: I don’t have any special expenses that add up to more than the standard deduction.
This form is the simplest way to file your taxes only if your combined income is less than $100,000 and you don’t have any dependents or qualify for any income adjustments, itemized deductions or credits.
SITUATION #2: I qualify for some adjustments (above-the-line deductions), but itemizing doesn’t make sense for me.
With this form you can take the standard deduction, plus it provides 12 possible adjustments that reduce your taxes without itemizing.
SITUATION #3: My deductions add up to more than the standard deduction.
USE: 1040 AND SCHEDULE A
You should get the money that’s due you by filling out the longer 1040 form. There are more adjustments available to taxpayers on the 1040 than there are on the 1040A. Fill out your itemized deductions on Schedule A and file it along with Form 1040.
SITUATION #4: My personal deductions don’t add up to more than the standard deduction, but I do have a part-time side business cleaning houses.
USE: 1040, SCHEDULE C AND SCHEDULE SE
Whether or not you itemize or take the standard deduction, you must fill out Form 1040 if you are claiming a business, even if it doesn’t show a profit. Record business expenses and your final profit or loss on Schedule C. If you made a profit of $400 or more, you must compute Schedule SE to calculate your self-employment tax. Report this amount in the Other Taxes section of Form 1040.