According to Decree No. 123/2020/ND-CP dated 19 October 2020 regulating invoices and certificates, Circuclars No. 78/2021/TT-BTC dated 17 September 2021 guiding the implementation of Decree No. 123/2020/ND-CP, Official Letter No. 2455/TCT-DNNCN providing guidelines on invoice and electronic tax certificates.