What is the Electronic Tax Transaction Authentication Code?

The concept of an electronic tax transaction account is specified in Clause 5, Article 3 of Circular 19/2021/TT-BTC on electronic transactions in the field of taxation. To be specific:

"Electronic transaction authentication code" is a one-time password used when taxpayers do not have a digital certificate to conduct electronic transactions. This password is sent from the electronic information portal of the General Department of Taxation or the systems of relevant agencies to the taxpayer's registered phone number; or via the taxpayer's email address registered with the tax authority; or it is randomly generated every minute by an automatic electronic device provided by the tax authority or a relevant agency; or it is randomly generated after a certain period by an application of the tax authority or a relevant agency and installed on smartphones or tablets.

Sincerely.