Official Letter No. 3955/CT-CS dated September 19, 2025 of the Tax Department provides guidance on declaring electronic invoices, especially how to record the buyer's tax code (MST). Declaring electronic invoices and recording buyer information correctly is always an important issue for businesses. According to the official letter, the name, address and MST of the buyer on the electronic invoice must be implemented in accordance with the provisions of Clause 5, Point c, Clause 14, Article 10 of Decree 123/2020/ND-CP, as well as the amendments and supplements at Point a and Point d, Clause 7, Article 1 of Decree 70/2025/ND-CP.
This article will provide detailed instructions on how to record the buyer's tax code on an electronic invoice, cases to note, and clearly indicate how to apply Official Dispatch No. 3955/CT-CS in practice, helping businesses to declare accurately and avoid the risk of being fined.
Legal basis related to Official Dispatch No. 3955/CT-CS
To help businesses understand the legal basis when declaring electronic invoices, the table below summarizes legal documents and official dispatches related to recording the name, address and tax code (MST) of the buyer. This information helps the application of Official Dispatch No. 3955/CT-CS become easy, accurate and fully compliant with the provisions of the law.
| Legal basis | Main content | Roles related to official dispatch 3955/CT-CS |
| Decree 123/2020/ND-CP | Clause 5, Point c, Clause 14, Article 10 | Regulations on how to write the name, address and tax code of the buyer on the electronic invoice. This is the basis for the official dispatch guiding the correct implementation of the regulations. |
| Decree 70/2025/ND-CP | Point a and point d, Clause 7, Article 1 | Supplement and amend regulations on buyer's tax code, helping businesses update and declare electronic invoices accurately according to new regulations. |
The role of Official Dispatch No. 3955/CT-CS
Official Letter No. 3955/CT-CS dated September 19, 2025 of the Tax Department plays a key role in guiding businesses to declare electronic invoices, especially the recording of the name, address and tax code (MST) of the buyer. The role of this official letter is not only in its legality but also directly affects the accounting - tax activities and transaction management of the business. Specifically, the main roles include:
Detailed instructions for compliance with legal regulations
Previously, businesses mainly relied on the general provisions in Decree 123/2020/ND-CP and the amendments and supplements in Decree 70/2025/ND-CP. However, these decrees are sometimes difficult to access and do not provide specific examples. Official Letter No. 3955/CT-CS provides detailed instructions on how to record the name, address and tax code of the buyer, helping businesses to declare correctly and completely, avoiding errors and violations of tax laws.
Support tax authorities to control transactions effectively
Accurately declaring buyer tax codes helps tax authorities monitor and check e-commerce transactions and internal transactions of enterprises. As a result, tax authorities can promptly detect non-transparent transactions or fraud risks, ensuring more effective tax management.
Ensuring transparency and legality for businesses
Enterprises that follow the instructions in the document will minimize the risk of being penalized for declaring incorrect information on invoices. This not only protects legal rights but also enhances reputation and trust from partners, customers and management agencies.
Serve as a reference basis for accounting and tax operations
Official dispatch No. 3955/CT-CS is considered an official and specific reference document for accountants, tax officers and corporate finance departments when declaring electronic invoices. Relying on this dispatch helps businesses build standardized, transparent and legally compliant internal processes.
Update new regulations, reduce legal risks
With the additions and amendments from Decree 70/2025/ND-CP, Official Dispatch No. 3955/CT-CS is an updated document, helping businesses quickly grasp new regulations on buyer tax codes, thereby minimizing errors and avoiding legal risks in declaring and storing electronic invoices.
Increase corporate governance efficiency and tax compliance
By correctly applying the instructions of the document, businesses not only fulfill their tax obligations accurately but also create transparent data, helping with more effective internal management, supporting easy preparation of financial statements and periodic tax reports.
In case the buyer has a tax code related to official dispatch no. 3955/CT-CS
According to Official Dispatch No. 3955/CT-CS, if the buyer is an organization, enterprise or business establishment with a tax code (MST), the electronic invoice must fully and accurately display the following information:
Business name or organization name
The name must be written exactly as it appears on the Business Registration Certificate, Branch Registration Certificate or legal documents issued by the state agency. Do not abbreviate, add or misspell the official registered name, as this may cause misunderstanding and affect the legality of the invoice.
Head office or branch address
The address must match the registration information in the tax records. In case the enterprise has many branches, it is necessary to clearly state the branch address that is granted the tax code to avoid confusion.
Buyer's tax identification number
This is the most important information, helping the tax authority to accurately identify the buyer. The tax code must be checked and verified accurately before issuing an invoice. Errors in the tax code (such as missing numbers, extra numbers, or wrong numbers) can lead to the invoice being considered invalid.
Information matching requirements
The buyer's name, address and tax code information on the invoice must match exactly with the legal records and tax registration data of the business. This is a mandatory condition for the invoice to be recognized as legal in case of inspection or comparison by the tax authority.
Consequences of incorrect tax code declaration
If the invoice is incorrect or missing the tax code, the invoice may not be accepted. value added tax (VAT) declaration or corporate income tax (CIT)Enterprises will lose the right to deduct input VAT and risk being administratively sanctioned for invoices and taxes according to current regulations.
Recommendations for businesses
Before issuing electronic invoices, businesses need to check the partner's tax code through the tax registration system or the General Department of Taxation's Information Portal. It is recommended to set up a tax code checking process in the accounting/electronic invoice software to minimize errors. In case of detecting errors after issuing invoices, businesses need to issue adjusted or replacement invoices according to regulations to ensure the invoice is valid.
In case the buyer does not have a tax code related to Official Dispatch No. 3955/CT-CS
According to the instructions in Official Dispatch No. 3955/CT-CS, in situations where the buyer does not have a tax code (MST), when creating electronic invoices, businesses need to note the following:
It is not required to state the name, address or tax code of the buyer.
When the buyer does not have a tax code, the electronic invoice is still legal even if the name, address or tax code information is not declared. This helps businesses avoid confusion or incorrect declaration of information when the buyer is an individual who is not doing business or has not registered for a tax code.
It is recommended to record other identifying information.
Although not required, businesses should still record other identifying information of the buyer such as:
- Full name
- Phone number
- Email or other contact address
This helps businesses easily manage transactions, store invoices and reconcile when necessary. At the same time, in case of disputes, invoices still have a basis for identifying the buyer to serve the purpose of checking and reconciling.
Ensure compliance with laws and transaction transparency
By recording this additional information, businesses both comply with the law on electronic invoices and increase transparency in transaction management. This is especially important for businesses with many small transactions with individuals or customers who have not registered for tax codes, helping to reduce the risk of tax audits.
Notes on storing and managing invoices
Alternative identification information should be fully stored in the enterprise's accounting and electronic invoice management system, for easy retrieval when needed to compare with actual transactions or serve tax authority inspections and audits.
Tax code information for individuals from June 1, 2025
To help businesses and accountants easily grasp the new regulations on recording tax code information (MST) or personal identification number on electronic invoices, Official Letter No. 3955/CT-CS has detailed instructions applicable from June 1, 2025. These changes are not only related to e-commerce transactions but also apply to traditional transactions, to ensure transparency and compliance with the law. Below is a summary of important points that businesses need to note:
| Content | Details according to official dispatch no. 3955/CT-CS |
| Time of application | From June 1, 2025, applicable to both traditional and e-commerce transactions. |
| General provisions | When the buyer is an individual, the electronic invoice must show the personal tax code or personal identification number. |
| Case 1: Individual with Tax Code | Enterprises are required to fully record personal tax codes on electronic invoices. |
| Case 2: Individuals do not have a Tax Code | If an individual already has a personal identification number in the National Population Database, the enterprise can use this number to replace the Tax Code. |
| Meaning of the regulation |
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| Benefits for businesses |
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| Requirements for deployment |
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Electronic invoices generated from cash registers related to Official Dispatch No. 3955/CT-CS
According to official dispatch No. 3955/CT-CS, for electronic invoices generated from cash registers, the invoice must display:
- Name, address and tax code or personal identification number of the buyer.
- Phone number if requested by buyer.
This makes electronic invoices not only legally valid but also easy to look up, check and compare information with tax authority data.
On tax exemption for business households related to Official Dispatch No. 3955/CT-CS
Another important content mentioned in Official Dispatch No. 3955/CT-CS is:
- Current tax laws and tax administration laws do not provide for tax exemption or reduction for business households converting to the declaration method.
- This means that when converting their business form, businesses must fully comply with the obligations to declare and pay taxes, and record tax codes on electronic invoices in accordance with regulations.
Important note when writing the buyer's tax code on the invoice related to Official Dispatch No. 3955/CT-CS
To ensure that electronic invoice declaration is carried out in accordance with legal regulations and avoid tax-related risks, businesses need to pay attention to some important points when recording the buyer's tax code. The table below summarizes essential notes based on Official Dispatch No. 3955/CT-CS, helping businesses control information, compare accurate data and make legal invoice declarations.
| Important content | Detailed instructions according to official dispatch no. 3955/CT-CS |
| Check tax code before issuing invoice | Before creating an invoice, businesses need to check and compare the buyer's tax code with the tax authority's database to avoid errors. This helps reduce legal risks and ensure valid invoices. |
| Make sure the information matches the documents | The name, address and tax code on the invoice must match exactly with legal documents such as the Business Registration Certificate, Branch Registration Certificate or Tax Code Notice issued by the tax authority. |
| Update personal tax code from June 1, 2025 | For individual customers who provide tax code or personal identification number, businesses are required to accurately record this information on electronic invoices according to new regulations. |
| Do not delete old data when making additional declarations | When declaring additional electronic invoices, businesses must not delete or edit old data. Any changes must be clearly explained to ensure transparency and avoid audit risks. |
| Display MST in invoice from cash register | With electronic invoices generated from cash registers, the buyer's tax code or personal identification number must be fully displayed. If requested by the buyer, a phone number can be added for easy checking and comparison. |
| Meaning of compliance with instructions | Fully implementing the above notes helps businesses avoid the risk of being fined, ensure valid invoices, transparency and easy comparison with tax authorities. |
Official dispatch No. 3955/CT-CS and practical application
In reality, many businesses have difficulty recording the buyer's tax code on electronic invoices, especially with individual customers or in transactions that combine online and traditional. If not done correctly, the invoice may be considered invalid, causing difficulties in tax declaration and reconciliation with tax authorities.
Official Letter No. 3955/CT-CS provides detailed instructions for businesses to know when to record Tax Code and when not to. Thanks to that, businesses avoid legal errors and declare electronic invoices accurately.
For individual customers, the document provides instructions on how to properly record tax codes or personal identification numbers, applicable uniformly from June 1, 2025. This helps tax authorities better manage individual transactions and ensure that businesses fully perform their tax declaration obligations.
In addition, Official Letter 3955/CT-CS also provides instructions on how to record the tax code on electronic invoices generated from cash registers, including displaying the name, address, tax code or personal identification number, and adding a phone number if requested by the buyer. This makes the invoice both legal and convenient for looking up, checking and comparing information with tax authority data.
Thanks to these guidelines, businesses can both comply with legal regulations and improve the efficiency of invoice management and tax declaration, while minimizing the risk of errors and penalties.
Conclude
Official Letter No. 3955/CT-CS is an important guidance document to help businesses declare electronic invoices in accordance with the law, especially regarding the name, address and tax code (MST) of the buyer. Fully applying the instructions from this document will help businesses avoid errors, ensure valid invoices and facilitate tax management and inspection.
In practice, recording the buyer's tax code, especially for individual customers and invoices generated from cash registers, always poses risks if not done correctly. Therefore, complying with the instructions of Official Letter No. 3955/CT-CS not only helps businesses meet their tax obligations, but also improves the efficiency of invoice management and transaction transparency.
To optimize the process of declaring and managing electronic invoices in accordance with the law, businesses can refer to solutions and specialized support from MAN – Master Accountant Network. Connect with MAN today to receive advice, update new regulations and ensure all invoice transactions are always legal and transparent.
Service contact information at MAN – Master Accountant Network
- Address: No. 19A, Street 43, Tan Thuan Ward, Ho Chi Minh City
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- Email: man@man.net.vn
