If you use TurboTax Online you have to use TurboTax Self-Employed if you have any business expenses or you have self-employment income that is not reported on a Form 1099-MISC. You can only use a lower edition if all your self-employment income is on a 1099-MISC and you have no expenses for your self-employed business.
You do have to select the edition you are going to use before you enter any data.
If you use the CD or download TurboTax software you can use any edition. TurboTax Home & Business would give you a more detailed interview and extra help for reporting self-employment, but if your situation is simple, or you are comfortable with the details of how to report it, one of the lower editions would be fine.
The amount or percentage of your income that is from self-employment is not a significant factor in deciding what program to use.
