What are regulations on reference number of e-invoices in Vietnam?

Reference number of e-invoices in Vietnam is specified at Point b, Clause 1, Article 4 of Circular 78/2021/TT-BTC, specifically as follows:

b) Reference number of an e-invoice contains 6 characters, including letters and numbers, indicating whether the invoice bears the tax authority’s identification code or not, year of issuance, and type of e-invoice. 6 characters are as follows:

- The first character: C if the invoice bears a tax authority’s authentication code; K if the invoice does not bear a tax authority’s authentication code;

- The next two characters are the last two digits of the year in which the e-invoice is issued, written in Arabic numerals. Example: 22 if the e-invoice is issued in 2022; 23 if the e-invoice is issued in 2023;

- The next character is either T, D, L, M, N, B, G or H depending on the type of e-invoice. To be specific:

+ T: E-invoices registered with tax authorities by enterprises, organizations or household businesses;

+ D: E-invoices used for sale of public property or national reserve goods or special e-invoices that do not have some mandatory contents of the “T” invoices;

+ L: E-invoices issued separately by tax authorities;

+ M: E-invoices generated by cash registers;

+ N: Electronic delivery and internal consignment notes;

+ B: Electronic delivery notes for goods sent to sales agents;

+ G: VAT invoices in the form of electronic stamps, tickets or cards;

+ H: Sales invoices in the form of electronic stamps, tickets or cards.

- The last two characters shall be decided by the seller to serve their management requirements. If the seller uses different forms of the same type of e-invoice, the last two characters shall be used to differentiate such e-invoice forms. If the seller does not decide the last two characters, YY shall be specified;

- The reference number and form number of an e-invoice shall be written on the upper right corner of the invoice (or a noticeable position);

- Examples:

+ “1C22TAA” - an authenticated VAT invoice issued in 2022 and registered with the tax authority;

+ “2C22TBB” - an authenticated sales invoice issued in 2022 and registered with the tax authority;

+ “1C23LBB” - an authenticated VAT invoice issued in 2023 and issued separately by the tax authority;

+ “1K23TYY” - an unauthenticated VAT invoice issued in 2023 and registered with the tax authority;

+ “1K22DAA” - an unauthenticated VAT invoice issued in 2022 and does not have some mandatory content of those registered with the tax authority;

+ “6K22NAB” - an unauthenticated delivery and internal consignment note issued in 2022 and registered with the tax authority;

+ “6K22BAB” - an unauthenticated delivery note for goods sent to sales agents issued in 2022 and registered with the tax authority.

Best Regards!