In the process of modernizing tax administration, related-party transactions are always a top focus of inspection and audit by the tax authorities. A very common situation that many accountants and business owners face today is: the 2024 corporate income tax return has been completed, but the required forms have been omitted from the final settlement. Decree 132/2020/ND-CP. In particular, for family businesses with overlapping ownership, identifying and declaring related-party transactions in the right time is key to avoiding unnecessary penalties. This article will analyze the real-world situation in depth and guide you through the safest process for handling this during the tax settlement period.
Identifying the relationship between the wife's company and the husband's company.
The actual situation is as follows:
“In 2025, the business had related-party transactions involving the purchase and sale of materials between the wife's and husband's companies, both located in Vietnam and paying the same tax rate. However, when filing the tax return in 2025, I did not include the related-party transaction appendix. Now, in 2026, if I file an amended return with the related-party transaction appendix, will I be penalized or have to pay any fees?”
Based on the actual situation, the purchase and sale of supplies takes place between a company owned by the wife and a company owned by the husband. To determine whether you are required to file an appendix to related-party transactions, you need to refer to Clause 2, Article 5 of Decree 132/2020/ND-CP.
The law stipulates it very clearly:
“"Individuals who have family relationships (spouse, parents, children, siblings, etc.) jointly control a business or have a significant influence on its operations are considered related parties."”
The purchase and sale of materials between these two legal entities in 2025, even with complete invoices and transparent payment, is still defined as a related-party transaction.
Many accountants mistakenly believe that if two companies operate independently, have separate tax identification numbers, and maintain separate accounting records, then no declaration is necessary. However, the potential risk here lies in the blood relationship and marital ties between the owners. Therefore, forgetting to attach the appendix when settling accounts in 2025 is a documentation error that needs to be corrected immediately by submitting a supplementary appendix on related-party transactions in 2026.
Why is it necessary to proactively submit supplementary related-party transaction appendices in a timely manner?
The current tax management process no longer relies on manual checks but has shifted to automated data reconciliation (Big Data). If you discover an error in 2026 for the 2025 tax period, proactively filing an amended related-party transaction declaration offers the following core benefits:
Compliance with the Tax Administration Law
Based on Article 47 Tax Administration Law No. 38/2019/QH14, Taxpayers who discover errors in their submitted tax returns are allowed to file supplementary returns within 10 years from the filing deadline, but this must be done before the tax authorities announce a tax audit decision. Your filing of the supplementary related-party transaction appendix in 2026 demonstrates your willingness to comply, helping your business avoid being blacklisted as a high-risk taxpayer.
Minimize the risk of being taxed.
Without the required appendix, tax authorities have the right to suspect that the business is deliberately concealing transfer pricing transactions. By submitting the supplementary appendix on related-party transactions, the company can make its material purchase and sale data more transparent, thereby protecting legitimate expenses when calculating corporate income tax.
Take advantage of penalty waiver policies.
In 2026, authorities are encouraging businesses to conduct self-assessments. If you complete the supplementary declaration of related-party transactions before being discovered by an audit, the penalty will be minimized, or even completely waived if no tax shortfall occurs.
To ensure the documentation is complete from the start, businesses can refer to the following: related party transaction documentation service To review the entire system of documents and records.
Risks of penalties when submitting supplementary related-party transaction appendices.
This is the part every business is concerned about: “Do I have to pay a penalty?” The answer depends on whether the error resulted in a tax shortfall.
Administrative penalties for procedural violations.
If you submitted your corporate income tax return on time (March 31, 2025) but only lacked the appendix, this is considered incorrect declaration of certain items in the return, but it does not result in a shortfall in tax amount. Decree 125/2020/ND-CP, If a business voluntarily submits an appendix to related-party transactions before an inspection decision is made, it has a high chance of being exempted from administrative penalties for false declarations under Clause 3, Article 9.
Conversely, if discovered by the tax authorities during an audit, the penalty for failing to provide complete information on related-party transactions can range from VND 2,000,000 to VND 8,000,000, depending on the severity.
Penalty 20% for outstanding tax and late payment penalties.
This risk only arises if the supplementary declaration of the related-party transaction appendix changes the cost of materials, leading to an increase in corporate income tax payable.
- Late payment penalty: Calculated at 0.031 TP3T/day on the amount of tax paid late.
- Penalty for incorrect declaration: 20% on the amount of tax underdeclared.
However, in a situation where both companies are located in Vietnam, have the same 20% tax rate, and no preferential treatment, the likelihood of incurring a 20% penalty is extremely low. This is because transferring profits from the wife's company to the husband's company (or vice versa) does not reduce the total tax revenue collected by the State; therefore, there is no evidence of tax evasion or erosion of the tax base.
Special situation: Two domestic businesses with the same tax rate.
This is a crucial point when filing a supplementary declaration for related-party transactions. In this spousal relationship, if both companies are applying the standard tax rate 20%, you need to pay attention to Article 18 of Decree 132/2020/ND-CP.
The right to be exempted from preparing a valuation report.
The law stipulates that if businesses are related but have the same tax rate and neither party enjoys tax incentives, they are exempt from the obligation to prepare National and Global Dossier. This helps businesses save a significant amount of consulting costs.
See details: No related-party transaction documentation is required.
Note: Exemption from filing does not mean exemption from declaration.
This is a fatal mistake many accountants make. Even if you are exempt from preparing documentation for determining the value of materials, you are still obligated to declare Appendix I. Forgetting to attach the appendix is still considered a deficiency in the legal documentation. Therefore, quickly update Appendix I with complete information on the transaction value of materials to complete your 2025 settlement documents.
However, to accurately identify these exemption criteria, you should consult an expert through related party transaction advisory services professional.
Instructions on how to submit supplementary declarations for related-party transactions on HTKK software.
To correct errors for the tax period, here are the steps to file an amended related-party transaction appendix:
- Step 1 – Log in to HTKK: Select form 03/TNDN, select the year 2025 and select the status as “Supplementary declaration”.
- Step 2 – Select the appendix: In the appendix list, select “Appendix to related party transactions (Form 01/TNDN)”. This is the most important step in the process of supplementing the appendix to related party transactions.
- Step 3 – Declare related party information: Enter the tax identification number, the name of the spouse's company, and determine the type of affiliated relationship.
- Step 4 – Enter transaction value: Fill in the total value of materials purchased or sold during the year. If the purchase and sale prices match the previously declared invoices, the tax figures will remain unchanged.
- Step 5 – Consolidation and Submission: After completion, the system will automatically input the data into the tax declaration form. If the tax amount does not increase, you simply need to digitally sign and submit it online.
Proactively filing supplementary related-party transaction appendices in this way helps you finalize your tax return safely, avoiding errors that may carry over into subsequent fiscal years.
Reference: Declare related-party transactions on HTKK.
Notes on the accuracy of transaction prices when filing supplementary declarations.
Even if two companies have the same tax rate, one should not be complacent about the unit price of materials when submitting supplementary declarations for related-party transactions. The tax authorities still have the right to check whether that price complies with the arm's length principle.
If you sell supplies to your spouse's company at an unusually low price compared to the market to help them reduce input costs, or sell at an excessively high price to increase their expenses, the tax authorities may reassess the price. Even if you have filed an addendum to the related-party transaction declaration, you may still be subject to retroactive corporate income tax collection if the reassessment increases the taxable profit of either party.
Advice from MAN – Master Accountant Network: Be prepared with quotations from other suppliers or similar contracts with independent parties for clarification if necessary. This preparation, along with the inclusion of an addendum to related-party transactions, will create a strong legal shield for the business.
Conclude
In summary, forgetting to submit the related-party transaction appendix is a correctable error. In a situation where two parent companies are subject to the same 20% tax rate, the financial risk is very low if you proactively and honestly declare the related-party transaction appendix in a timely manner.
Understanding the regulations regarding supplementary declarations of related-party transactions not only helps protect your business's finances but also builds a good reputation with tax authorities.
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Content production by: Mr. Le Hoang Tuyen – Founder and CEO of MAN – Master Accountant Network, CPA Vietnam with over 30 years of experience in accounting, auditing, and financial consulting.