Symptoms
Provider cannot change any details on Account General screen. The error is displayed:
Tax Registration ID is incorrect.
Even without changing anything details cannot be saved.
Cause
Tax registration ID does not correspond to regular expression specified for this country.
Regular expression is configured at Home>System>Settings>More Finance Settings>Country Specific Settings> [country]>Regular expression for personal/company Tax ID in PBA-E 5.5 and Home>Configuration Director>Sales & Financial Settings>Country Specific Settings> [country]>Regular expression for personal/company Tax ID in PBA-E 5.4.
Resolution
Correct Tax registration id of the account, so it correspond to regular expression.