⚠️ FROM JULY 1, 2026: BUSINESSES WILL HAVE ONLY FIVE YEARS
TO VOLUNTARILY FILE SUPPLEMENTARY TAX RETURNS
💭 Many businesses still assume: “If an error is discovered several years later, we can simply file a supplementary tax return.”
⏳ From July 1, 2026, this approach needs to change.
📚 Under he 2025 Law on Tax Administration, taxpayers may file supplementary tax returns only within 05 years
from the statutory filing deadline for the tax period in which the error occurred.
❓ What happens if an error is discovered after five years?
❌ The taxpayer may no longer be entitled to file a supplementary tax return for that tax period,
except in specific cases prescribed by law.
🚨 This means that businesses may lose the opportunity to voluntarily correct their own tax filing errors.
📌 Do not assume that “after five years, there is no further liability”
⚠️ This is a point that many businesses may easily misunderstand.
⏱️ The five-year period is only the time limit within which taxpayers may voluntarily file supplementary tax returns.
It does not mean that:
❌ Outstanding tax liabilities are written off;
❌ Accounting errors may be disregarded; or
❌ Tax authorities no longer have the power to conduct inspections or impose measures within the
applicable statutory limitation periods.
📋 Businesses may still be required to:
✔ Adjust their accounting records and financial statements in accordance with accounting regulations where material misstatements exist;
✔ Maintain complete supporting documents, records, and explanatory materials; and;
✔ Assess tax risks for periods that remain within the applicable limitation periods.
🚨 Where do the greatest risks arise?
1️⃣ Case 1: Under-declared tax liabilities
🔍 A business discovers an error more than five years later:
➡️ It may no longer be entitled to file a supplementary tax return.
➡️ It must still make the necessary accounting adjustments and prepare supporting explanations in case of a tax inspection.
2️⃣ Case 2: Over-declared tax liabilities
⚠️ This situation may be even more concerning.
🧾 Examples include:
🔸 Over-declared revenue;
🔸 Overpaid Corporate Income Tax (CIT); or
🔸 Under-declared deductible expenses…
⏳ Once the five-year period has expired:
👉 The business may no longer have a basis for filing a supplementary return to reduce its tax liability
or address the overpaid tax amount.
📌 In other words:
🚫 The business risks losing the opportunity to proactively protect its legitimate tax interests.
✅ What should businesses do now?
⛔Do not wait until a tax inspection is announced before reviewing your tax records.
📅 Businesses should establish an annual tax review plan covering:
✅ Reconciliation of input and output invoices.
✅ Review of Value-Added Tax (VAT) declarations.
✅ Review of Corporate Income Tax (CIT) finalization returns.
✅ Review of Personal Income Tax (PIT) finalization returns.
✅ Reconciliation of receivables and payables.
✅ Review of related-party transactions, where applicable; and
✅ Review of eligibility for tax incentives.
⏰ Where errors are identified, supplementary tax returns should be filed before the five-year time limit expires.
🗓️ Key deadlines businesses should pay particular attention to
| Tax return year | Recommended review completion date |
|---|---|
| 2021 | Before March 31, 2027 |
| 2022 | Before March 31, 2028 |
| 2023 | Before March 31, 2029 |
| 2024 | Before March 31, 2030 |
| 2025 | Before March 31, 2031 |
📝 The above timeline assumes that the standard deadline for filing an annual tax finalization return
is March 31 of the following year. The actual deadline must be determined based on the statutory
filing deadline applicable to each specific tax return.
🔎 Practical Perspective
The new regulation not only reduces the time limit for filing supplementary tax returns from ten years to five years,
but also changes how businesses should manage tax risks.
🔄 Instead of waiting until the tax authorities conduct an inspection, businesses should proactively
carry out annual reviews to identify and address errors in a timely manner.
📣 This is expected to be one of the regulatory changes with a significant impact on accounting and
tax risk management in the coming period.
☎️ Has your business reviewed its tax returns from previous years?
If not, now is an appropriate time to conduct a review before the right to voluntarily file supplementary tax returns
expires under the new regulations.
📌 Disclaimer: This post is intended solely to provide general information on legal regulations.
The appropriate treatment of each specific case must be determined based on the Law on Tax Administration,
applicable accounting regulations, and the actual records and circumstances of the business.
📞 Take a proactive approach to reviewing your tax records and minimizing tax risks. Contact MBA for assistance in
reviewing your documentation and recommending an appropriate course of action.
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