If you have enabled Two-Factor Authentication (2FA) for your login into TaxCalc you may experience an Authentication code incorrect, please try again message similar to the screen shot below.
The common reasons for this happening are:
The first is that the date and time on your computer may not be synchronised with the device you're use to authenticate with. In that case please see the knowledge base article: How do I synchronize my system date and time to use authentication applications?
The second is that depending on which authenticator application you have used it may have temporarily become out of sync. In those cases please wait for the next code to be generated in the authenticator app and try again. To explain further, some authenticator apps, like the Microsoft one, generate a code available which resets on each minute, and after 30 seconds from each minute. Other authenticator apps, like DUO, generate a code which lasts for 30 seconds from when the QR code is scanned. The TaxCalc application requires a code which matches the the computer time, so if using Duo say and the time goes into the next minute you may need to wait for the code to be regenerated.
The third is if you have Passwordless signing enabled for the account used within the authenticator app, and in those cases an 8 digit code may be provided. We would recommend registering a different account within that authenticator app, or to look at disabling Passwordless signing temporarily or to use a different authenticator app. There is more information available from a Google Search here about Passwordless signing.
For additional information please see What is Two-Factor Authentication?