In order to prepare and file a child's tax return, you will need to set up a separate account. Your child's account needs to have its own unique username and password. Don't include your child's income on your tax return. Please note that very few children need to file a tax return because their income isn't usually high enough to be required to file a tax return. See
Chart B from the
Form 1040 instructions to figure out if your child needs to file a tax return.