The current rejection stems from the SSN already being flagged as "used" within the IRS database. Because this validation occurs at the agency level after transmission, neither our local software nor the intermediary servers have a mechanism to preemptively detect the match. The issue lies solely in the IRS/SSA database.

Given the unfortunate rise in identity theft, encountering multiple occurrences in a single day, while rare, is certainly possible. However, if this trend persists, it would be prudent to conduct a thorough audit of your local servers and hardware to rule out a localized data breach.

Should you determine that a security incident has occurred, please ensure you follow the protocols outlined in your Written Information Security Plan (WISP). As you know, the IRS and state agencies will require documentation of these procedures in the event of an inquiry.

In the meantime, obtaining an IPPIN for the primary taxpayer will allow you to efile the return. 

@hcliston