No, TurboTax does not currently charge a fee to file amended tax returns. However, TurboTax would charge a fee if it was determined that the reason you needed to file amended tax returns was a situation that required a product upgrade, i.e. Free Edition to Deluxe, etc.
"TurboTaxEdwardK TurboTax Tax Support Agent"
Please see the following TurboTax FAQ for instructions on how to amend your tax return: