To amend a return in TurboTax that was originally completed using a different service, you would first have to open an account and then prepare a return in TurboTax that exactly matched the return you filed with TaxSlayer. Once you get it to exactly match, then you can start an amended return.
You may need to pay for the account to prepare your matching original return unless you are able to use the Free Edition. What you can do with the free edition is fairly limited. Look at your return you did with TaxSlayer. Were there any Schedules 1-6 in that tax return? If there were, you would have to upgrade to at least Deluxe in TurboTax which is $39.99 for federal and $39.99 for state. There would be no additional fee to amend the return unless the additional tax documents you received required an upgrade to higher than Deluxe.
