The Vietnam GDT e-invoice guide for finance teams

All businesses issuing invoices in Vietnam must register e-invoice templates with the GDT and transmit issued invoices to the central registry. Buyers can verify any invoice against the registry using its serial and the seller's MST. Two variants exist: invoices with a tax authority code, issued through the GDT's coding service, and invoices without a code, used by qualifying enterprises that transmit data to the tax authority on a defined schedule. Both are valid; both are verifiable.

• Decree 123/2020/ND-CP sets the legal framework for electronic invoices and records in Vietnam.
• Circular 78/2021/TT-BTC provides implementation guidance, including invoice templates, serial formats and the transition timetable that made e-invoicing mandatory nationwide from 1 July 2022.
• Input VAT deduction depends on holding a valid invoice. An invoice that was never properly registered is not a deductible document, regardless of whether you paid it.
• Non-cash payment requirements still apply for VAT deduction on higher-value purchases — an e-invoice alone does not substitute for the payment evidence.
• Invoices can be replaced or adjusted, but the replacement references the original. Buyers must keep the chain, not just the latest file.

A Vietnamese e-invoice is an XML file, usually accompanied by a human-readable PDF rendering. The XML is the legal document; the PDF is a convenience copy. Key fields buyers depend on are the seller and buyer MST, the invoice template symbol and serial, the invoice number, the issue date, the line detail with VAT rate per line, the totals before and after VAT, and — for coded invoices — the tax authority code. When a supplier emails only the PDF, ask for the XML: without it, verification and automated posting both degrade to manual work.

• Seller MST is active and matches the supplier on the invoice and in your supplier master.
• Invoice serial and template are registered with the GDT.
• Issue date is within the supplier's authorised range and the correct VAT period.
• Invoice total, VAT rate and VAT amount match the registered values and the underlying purchase order.
• Buyer MST is correct — an invoice issued to the wrong entity in your group is not deductible by the entity that paid it.
• The invoice has not already been received and paid under another store, branch or cost centre.

Suppliers issue through a range of authorised providers, and each renders and delivers files slightly differently. In practice a mid-sized Vietnamese buyer receives invoices from Viettel Invoice, VNPT Invoice, MISA meInvoice, BKAV eHoadon, FPT and several smaller platforms in the same month. Any process that assumes a single layout or a single delivery channel breaks within weeks. Robust intake means accepting XML and PDF from email, portals and manual upload, then normalising them into one internal representation before validation.

• Adjusted or replacement invoices: match the replacement to the original, reverse the earlier accrual and keep both documents linked.
• Inactive seller MST: hold the invoice and query the supplier before payment — this is the highest-risk exception for VAT deduction.
• PDF-only delivery: request the XML; validate manually against the registry in the meantime and record the result.
• Foreign supplier invoices: outside the GDT regime entirely, so route them to a separate workflow with contract and withholding tax checks.
• Late invoices arriving after period close: post to the correct period per your accounting policy, and track the VAT timing implication explicitly.

Validating every invoice manually doesn't scale once you process more than a few dozen a week. BancoOS calls the GDT registry on every inbound invoice automatically, stores the registry response as audit evidence, matches the invoice to its purchase order and goods receipt, and only escalates true exceptions to finance. The approved result posts to MISA, Business Central or your existing ERP, so the accounting system receives clean, already-verified entries.

• Every invoice in the period has a stored registry response, not just a PDF.
• No open exceptions for inactive MST or unregistered serials.
• Adjustment and replacement chains are complete and linked.
• Input VAT claimed reconciles to the validated invoice set.
• Duplicates across branches and cost centres are zero.