I used it just fine for 2021 returns, but this year so far, I've had major problems with people passing the authentication. I'm still set to use Knowledge Based. I've only had 2 out of 7 pass authentication, and most people are saying the questions don't have valid responses to their personal data. These same people were able to authenticate just fine last year, and haven't had major changes such as changing addresses. Something seems wrong, here. I've called Support but so far, they are clueless. I've reached out to the person who sold me the signatures to see of another avenue to get help for this.