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🇻🇳 Vietnam - Invoicing Specifications (GDT e-Invoice)

Status: 🔴 Mandatory Clearance (For nearly all businesses) Authority: GDT (General Department of Taxation) System: Hoadondientu (Electronic Invoice System)

1. Context & Roadmap

Vietnam mandates a Clearance system where invoices must be authenticated by the Tax Authority before being sent to the buyer (for most companies). Crucial Distinction:

  • Invoice with Code: Standard model. GDT generates a unique code for each invoice.
  • Invoice without Code: Reserved for specific sectors (Utilities, Banking, Telco) with high volume and trusted ERPs.
DateScopeObligation
ActiveAll BusinessesMandatory e-invoicing (Decree 123/2020).
Jan 1, 2026New Decree 70Stricter rules for e-commerce and POS integration.
OngoingVAT Reduction8% VAT rate extended until Dec 2026.

2. Technical Workflow (Authenticated Invoice)

Invoicerr must connect to a T-VAN provider (Value Added Network) to reach the GDT.

sequenceDiagram
    participant S as Invoicerr
    participant TVAN as T-VAN Provider
    participant GDT as Tax Authority
    participant B as Buyer
    
    Note over S: 1. Generate XML
    S->>S: Map to Decree 123 Format
    S->>S: Sign with Digital Cert (USB/HSM)
    
    Note over S: 2. Request Code
    S->>TVAN: Send Signed XML
    TVAN->>GDT: Forward Request
    GDT->>GDT: Validate & Assign Code
    GDT-->>S: Return "CQT Code" (Tax Authority Code)
    
    Note over S: 3. Finalize & Send
    S->>S: Embed CQT Code in Invoice
    S->>B: Send XML + PDF (with Code)

🧱 Key Components

  1. CQT Code (Mã của cơ quan thuế): A unique string generated by the GDT. Without this, the invoice is invalid (for the "With Code" model).
  2. T-VAN: Intermediary service providers licensed to transmit data to GDT.
  3. Digital Signature: Mandatory. Usually a USB token or HSM-based signature (local standard).

3. Data Standards & Requirements

A. Format: XML (Decree 123)

  • Syntax: Specific XML schema defined by Circular 78/Decree 123.
  • Signature: Must use a certificate issued by a Vietnamese CA.

B. Critical Fields

  • Form Number (Mẫu số): e.g., 1 (VAT Invoice), 2 (Sales Invoice).
  • Symbol (Ký hiệu): e.g., C26... (C=Code, 26=Year).
  • Buyer Info: Tax Code (MST) is mandatory for B2B.

4. Adjustments & Errors (Form 04/SS-HDDT)

Correction is strict. You cannot simply delete an invoice.

  • Form 04/SS-HDDT: Must be submitted to GDT to report errors.
  • Adjustment Invoice: Issued to correct value/quantity (linked to original).
  • Replacement Invoice: Issued to replace a wrongly issued invoice (linked to original).

5. Implementation Checklist

  • T-VAN Connection: Partner with a local T-VAN provider (e.g., BKAV, Viettel, VNPT). Direct GDT connection is hard.
  • Digital Signature: Support integration with local USB tokens or cloud signing services.
  • Code Storage: Store the returned CQT Code and render it clearly on the PDF representation.
  • Adjustment Logic: Build flows for "Adjustment" and "Replacement" invoices referencing the original ID.

6. Resources