TT600 errors, including TT600, TT601, TT602, TT603, AND TT604, are typically validation errors. This means you may have entered something into your return that TurboTax cannot understand or has not been programmed to accept.
Examples are: quotation marks, ampersands and other special characters in any fields that accept text, such as your name, address, your dependant’s names, etc.
If you are still not able to resolve this issue, please contact our phone support team for more assistance.