My return was Efiled and accepted but I had to amend my return. Do I need to mail all pages of the return or just the 1040X?

[DanaB]

You will need to mail the Form 1040X with any forms and schedules that caused the change. For example, if you itemized instead of using the Standard Deduction then you would include Schedule A. Or if you had to add another W-2 you will include the added W-2.