The description for IRS reject X0000-005 is "The XML data has failed schema validation". A schema is the set of rules describing how the e-filed return data should be organized and validated. The reject message will generally include additional information regarding which aspect of the schema has failed.
This reject occurs when the return as e-filed does not fit the current schema, and this mismatch generally occurs when a return that was completed before a schema change is transmitted after the IRS has begun using the new schema to validate returns.
The first step to resolving the reject is to update the TaxSlayer Pro software. If you are working in a networked environment with more than one computer working on tax returns, be sure to update the computer designated as the file server first, then update the workstations.
After updating the software, reopen the return to pull in the update, then retransmit. If it continues to reject for the same reason, contact TaxSlayer Pro Customer Support for assistance.