Legal regulations related to the adjustment of tax dossiers

The following article analyzes the current situation and legal regulations concerning the adjustment of tax dossiers, and addresses several frequently asked questions.

I. Current situation related to the adjustment of tax dossiers

The emergence of the need to adjust tax dossiers

• In practice, the preparation and submission of tax dossiers frequently involve errors such as under-declaration, incorrect items, inaccurate accounting figures, or improper application of newly issued tax policies.
• Cases requiring adjustment are commonly concentrated in value-added tax (input VAT credit and tax refunds), corporate income tax (deductible expenses and accumulated losses), and personal income tax (miscalculation of taxable income or number of dependents).
• Frequent changes in tax policies and guiding regulations also make it difficult for enterprises and individuals to fully comply from the outset.

Impact on enterprises and taxpayers

• Upon discovering errors, taxpayers are required to prepare supplementary and adjusted tax dossiers, which increases time costs and administrative procedures.
• Failure to make timely adjustments may result in tax arrears assessments, late payment interest, or administrative sanctions. 
• Certain enterprises deliberately fail to make adjustments or submit inaccurate supplementary declarations, leading to serious legal risks and, in severe cases, criminal liability for tax evasion or fraud.

Difficulties and limitations

• Although the procedure for adjusting tax dossiers has been simplified, it remains complex for small enterprises and individual taxpayers.
• A lack of timely and detailed support from tax authorities may cause delays or errors in the adjustment process.
• The rate of proactive supplementary declarations remains low, with most adjustments being made only after detection through tax inspections or audits.

II. Legal regulations related to the adjustment of tax dossiers

During the process of tax declaration and fulfillment of tax obligations, enterprises may incur errors or omissions requiring adjustment. The law provides specific regulations to ensure that tax dossier adjustments are conducted transparently, in accordance with procedures, and with minimized legal risks.

1. What is the adjustment of a tax dossier?

The adjustment of a tax dossier is a legal act aimed at amending or supplementing inaccurate or incomplete information in a previously submitted tax return, in order to ensure that the declared figures are consistent with actual business operations and legal requirements.

It constitutes both a right and an obligation of the taxpayer to ensure the accuracy and truthfulness of tax filings and to avoid legal risks arising from incorrect declarations.

2. When is the enterprise required to adjust its tax dossier?

Pursuant to Article 47 of the Law on Tax Administration 2019, as amended in 2025, the enterprise is required to adjust its tax dossier in the following cases:

Where a taxpayer discovers errors or omissions in a tax return already submitted to the tax authority, the taxpayer is entitled to submit a supplementary tax return within ten (10) years from the expiry date for submission of the tax return of the relevant tax period in which the errors or omissions occurred, provided that:

• The adjustment is made before the tax authority or competent authority announces a decision on inspection or audit;
• The dossier does not fall within the scope or period subject to tax inspection or audit as stated in the inspection or audit decision.

For matters falling within the scope of inspection or audit, the taxpayer may submit additional explanatory documents in accordance with tax laws, inspection laws, and conclusions or regulations of competent specialized authorities relating to the determination of tax obligations.

3. How is the procedure for adjusting tax dossiers regulated by law?

According to Clause 4, Article 47 of the Law on Tax Administration 2019, the dossier for adjusting a tax return includes:

• A supplementary tax return using Form No. 01/KHBS issued together with Circular No. 80/2021/TT-BTC;
• An explanatory statement for the supplementary declaration and relevant documents using Form No. 01-1/KHBS in Appendix II issued together with Circular No. 80/2021/TT-BTC.

The procedure for adjusting tax dossiers is guided in Clause 4, Article 7 of Decree No. 126/2020/NĐ-CP, as follows:

Where the supplementary declaration does not change the tax obligation, only the explanatory statement and relevant documents are required; submission of a supplementary tax return is not required.

• If the annual tax finalization return has not yet been submitted, the taxpayer shall submit a supplementary declaration for the month or quarter in which errors or omissions occurred, and concurrently consolidate the adjusted figures into the annual tax finalization dossier.
• If the annual tax finalization return has already been submitted, only the annual tax finalization return shall be supplemented; in the specific case of supplementary declarations for personal income tax finalization returns of organizations or individuals paying salaries or wages, the corresponding monthly or quarterly returns with errors or omissions must also be supplemented.

Where the supplementary declaration results in an increase in tax payable or a reduction in tax refunded by the state budget, the taxpayer must fully pay the additional tax payable or the excess refunded amount, together with late payment interest (if any), into the state budget.

Where the supplementary declaration only increases or decreases the amount of value-added tax eligible for carryforward deduction, it shall be declared in the current tax period. The taxpayer is only entitled to supplement an increase in VAT refundable amounts where the tax return for the subsequent tax period has not yet been submitted and no tax refund application has been filed.

III. Questions on the adjustment of tax dossiers

1. Can a third party be authorized to adjust a tax dossier?

Taxpayers are entitled to authorize organizations providing tax procedure services (tax consulting firms, tax agents) or individuals duly licensed to practice tax services to declare, submit, and adjust tax dossiers on their behalf.

Such authorization must be made in writing, confirmed by the parties, and the authorized party shall take legal responsibility within the scope of authorization.

2. What is the maximum time for adjusting a tax dossier after discovering errors?

Pursuant to Article 47 of the Law on Tax Administration 2019, as amended in 2025, taxpayers may submit supplementary tax returns within ten (10) years from the expiry date for submission of the tax return of the tax period in which errors or omissions occurred, provided that the conditions regarding inspection and audit stated above are satisfied.

Accordingly, the maximum duration for adjusting a tax dossier is ten (10) years from the expiry date for submission of the tax return of the relevant tax period.

3. Can a tax dossier be adjusted multiple times for the same tax period?

The law does not limit the number of times a supplementary declaration or adjustment may be made. Taxpayers may adjust multiple times if new errors are discovered. However, the most recent supplementary dossier shall serve as the final basis for determining the tax obligation for that tax period. 

4. If the adjustment results in a reduction of tax paid, is a tax refund available?

If a supplementary declaration demonstrates that the tax payable is lower than the amount already paid, the taxpayer may choose to offset the excess amount against tax obligations of subsequent periods or apply for a tax refund in accordance with the procedures stipulated in the Law on Tax Administration 2019 and Circular No. 80/2021/TT-BTC.

However, in such cases, the tax authority typically conducts thorough verification before approving the refund.

5. Does the adjustment of tax dossiers apply to personal income taxpayers?

Pursuant to Clause 1, Article 47 of the Law on Tax Administration 2019, taxpayers discovering errors or omissions in submitted tax returns are entitled to submit supplementary declarations within ten (10) years from the expiry date for submission of the relevant tax return. According to Article 2 of the same Law, taxpayers include not only organizations but also individuals.

Accordingly, in addition to enterprises, individuals subject to personal income tax are also entitled to supplement and adjust their personal income tax finalization dossiers upon discovering errors (e.g., incorrect declaration of dependents, withheld tax amounts, or deductible items).

The supplementary declaration procedure for individuals is implemented using the prescribed personal income tax supplementary forms and submitted to the directly managing tax authority.

IV. Legal consulting services related to the adjustment of tax dossiers

Legal consulting services related to the adjustment of tax dossiers include:

• Advising on legal grounds and guiding procedures for supplementary declarations and tax dossier adjustments;
• Reviewing and identifying errors in tax dossiers of enterprises and individuals;
• Representing or assisting taxpayers in working with tax authorities in cases of difficulties;
• Advising on handling options where supplementary declarations result in additional tax payable, tax arrears assessments, or tax refund applications.

Should you have any questions regarding the adjustment of tax dossiers or other legal matters, please contact NPLaw for direct consultation and guidance.