Tax audits in Vietnam: how companies are selected, what happens on site and how to prepare

A foreign-invested enterprise (FIE) in Vietnam is audited when the tax authority decides that its data warrants a closer look, and that decision is increasingly driven by risk analysis rather than by a fixed rotation. Mismatches between returns and e-invoices, large refund claims, persistent losses in an expanding business, heavy payments to related parties abroad and transactions with suppliers flagged in the tax system are the kinds of signals that raise a company's profile.

Most reviews start at the tax office as a desk review and end there if the company answers well. Some turn into an on-site audit at the company's premises, covering selected taxes and periods. Either way, the company that has kept its own file in order — reconciliations done, contracts matching invoices, intercompany charges documented — spends days on an audit rather than months. This guide describes the process and how to prepare, without going into penalty levels.

How companies come to be selected

The Law on Tax Administration (Law 38/2019/QH14) provides for audits at the tax office and at the taxpayer's premises, and for inspections. From 1 July 2026 the approach to classifying taxpayers by risk is governed by Circular 94/2026/TT-BTC on compliance management and risk management in tax administration. We name it for reference and do not summarise its criteria; what can be said is how the underlying data looks from the company's side.

Signals that commonly draw attention in FIEs:

• Returns that do not match e-invoices. Output VAT below the value of invoices issued, input VAT above the invoices received.
• VAT refund claims, especially large or repeated ones. Refunds are often checked before or after payment.
• Losses year after year while revenue, headcount or capacity grows.
• Significant related-party transactions — management fees, royalties, interest, purchases from or sales to group companies. The tax administration of related-party transactions is governed from 1 July 2026 by Decree 255/2026/NĐ-CP.
• Counterparties with problem statuses, such as suppliers not operating at their registered address.
• Changes in structure — mergers, capital transfers, closure of branches, or the end of an incentive period.

None of these means a company has done anything wrong. They are simply where the authority's data points first.

Desk review: the first and often the last step

In a desk review, the managing tax office compares a company's returns with the data available to it and, if something does not fit, sends a notice asking for an explanation or additional documents. The company replies in writing within the time given.

A good reply has three parts: the figures reconciled line by line, the documents that support the reconciliation, and — where the review has found a genuine error — a supplementary return correcting it. A reply that argues without numbers, or that arrives after the deadline, tends to move the matter to the next stage.

Hypothetical example. Suppose a notice states that the input VAT a company declared for a quarter exceeds the VAT on purchase invoices recorded for it in the e-invoice system by VND 85 million. The company's reconciliation shows three causes: import VAT paid at customs, which is not in the e-invoice system but is supported by customs declarations; one supplier invoice declared twice by mistake; and one invoice from a supplier whose issuance had not reached the system at the time. The reply sets out each item with its documents, and a supplementary return withdraws the duplicated invoice. That is a complete answer. Arguing that "the figures are correct" without the breakdown would not be.

Keep a copy of the notice, the reply and the acknowledgement together. If the same question is raised again in a later audit, the file shows it was already answered.

On-site audit: from notice to conclusion

An on-site audit follows a formal sequence. The details are set by the tax administration rules in force for the audit date, now including Decree 252/2026/NĐ-CP and Circular 89/2026/TT-BTC; the outline below is the typical shape:

1. Audit decision. The company receives a written decision naming the audit team, the taxes and periods covered and the duration. Read the scope carefully: the audit is limited to what the decision states.
2. Opening meeting. The team explains the scope and the documents it expects. Agree a single contact person on the company side and a room where documents can be reviewed.
3. Fieldwork. The team reviews books, invoices, contracts, bank records and the reconciliations behind the returns, and asks questions. Answer in writing where possible, and keep a log of every document provided.
4. Minutes. Findings are recorded in audit minutes (biên bản). The company can record its disagreement and explanation in the minutes. Do not sign minutes you have not read in full; ask for time to review if needed.
5. Conclusion or decision. The authority issues its conclusion and, where relevant, a decision on additional tax, late-payment interest and any penalties.

A company that disagrees with a decision can file a complaint under the complaint procedures, and ultimately take the matter to court. Keep deadlines for complaints in view from the day the decision arrives.

What auditors typically ask for in an FIE

Most of these are the same reconciliations a well-run finance team produces for its year-end close. The difference in an audit is that they must be in Vietnamese or translated, tied to the filed returns, and available quickly.

Keeping an audit-ready file

The cheapest audit preparation happens during the year. A practical minimum for each tax year:

• Monthly or quarterly reconciliations of VAT returns against the e-invoice portal, signed off and dated.
• Annual reconciliation of revenue across ledger, invoices and bank, and of the e-tax account balance against the ledger.
• A contract index linking each significant supplier and customer contract to its invoices.
• An intercompany file with agreements, invoices, evidence of services and the pricing basis for each charge.
• A counterparty check log showing supplier status checks and the follow-up on any flags.
• The filed returns with system acknowledgements, payment proofs and any correspondence.

Accounting documents used directly for bookkeeping and preparing financial statements must be kept for at least 10 years under the Law on Accounting, so the file has to survive staff changes and system migrations. Store it where a successor can find it.

Our sister site ThueSach.com (in Vietnamese) has practical guides to reviewing a company's tax records before they are reviewed for you.

Handling an audit well

• One voice. Nominate a single contact who knows where everything is and who speaks for the company. Conflicting answers from different staff create more questions than they answer.
• Answer what is asked. Provide the documents requested, clearly labelled, and keep a copy of each set. Do not volunteer unrelated material, but never withhold or alter documents.
• Put explanations in writing. Oral explanations are easily lost; a written note attached to the minutes is not.
• Involve the parent early. If an intercompany charge is questioned, the evidence usually sits with the group. Ask for it on day one, not on the day before the minutes are signed.
• Close the loop. After the conclusion, fix the process that caused each finding, so that the same point does not come back in the next audit.

Before an audit starts, check your own position in the e-tax account and the e-invoice portal, and confirm your managing office through the taxpayer information lookup. The auditors will have looked at the same data.