Enterprises finalizing annual corporate income tax (CIT) must use Form No. 03/TNDN issued together with Appendix I of Circular 89/2026/TT-BTC (effective from 01/7/2026). Form 03/TNDN under Circular 80/2021/TT-BTC has been abolished. The return is accompanied by a system of appendices — below are the verified appendices and the transition rules every enterprise should know.
Transition rules: two milestones to distinguish clearly
Under Article 100 of Circular 89/2026/TT-BTC:
- 2025 finalization (dossier filed in 2026): still use the form under Circular 80/2021/TT-BTC.
- From the 2026 finalization period (dossier filed in 2027): use the new Form 03/TNDN under Circular 89/2026/TT-BTC.
Appendices accompanying Form 03/TNDN
Appendices verified against Appendix I of Circular 89/2026:
- 03-1A/TNDN — Business results (mandatory for manufacturing, trading and services);
- 03-2A/TNDN — Loss carry-forward (note: the code “03-2A” follows Circular 89/2026, unlike “03-2/TNDN” under Circular 80/2021);
- 03-3A/TNDN — CIT incentives (including code 0270 for SMEs entitled to a 3-year tax exemption).
The appendix system also includes: 03-1B/1C, 03-3B/3C/3D, 03-4 (with Part B on the global minimum tax), 03-5, 03-6, 03-8/8A/8B/8C, 03-9 and the related-party transactions appendix (GDLK). When preparing an actual dossier, enterprises must check the original Appendix I of Circular 89/2026 to determine the full set of appendices required for their actual circumstances.
What is new: CIT rates under Law 67/2025/QH15
The Law on Corporate Income Tax 67/2025/QH15 applies from the 2025 tax period. Per the finalized brief, the rates are: 20% (standard), 15% (revenue up to VND 3 billion), 17% (revenue above VND 3 billion up to VND 50 billion) — declared at indicator [C7] on the return. In practice, cross-check Article 10 of Law 67/2025/QH15 to determine the exact rate applicable to your enterprise.
Notes when preparing the finalization dossier
- Identify the correct finalization period to use the right form (2025 uses the old form, 2026 the new one).
- Distinguish mandatory appendices (such as 03-1A for manufacturing-trading-services) from appendices required by actual circumstances (loss carry-forward, tax incentives, related-party transactions, and so on).
- Check the original Appendix I of Circular 89/2026 directly before filing — do not file based on reference lists alone.
Need support with CIT finalization? Contact FLAT Law Firm for advice.
The information above is for reference only and does not constitute legal advice. This content was drafted by AI and reviewed by the QA council of FLAT Law Firm.
