If you are reporting net self employment income on Schedule C, you can use business related expenses incurred on your credit card as a tax reduction. Any other non-business related expenses on your credit card is non-deductible commercial expense.
You typically file an amend tax return in TurboTax Online (TTO) by signing in and selecting the "amend" option for the year you wish to adjust. When you first enter the amended return, it will ask the reason for amending and you select the sections you need to revisit. Your refund registers should drop to zero at that point as the amendment refund or tax due amount reflects the difference between the original return and the corrected return. You may also need to indicate the refund received or tax paid per the original return. A 1040X form will be generated along with an amended copy of your return reflecting the changes when you are done.
