Filing supplementary tax returns on the electronic tax system is done when taxpayers discover errors in their previously submitted returns, such as missing invoices, incorrect revenue figures, incorrect indicators, or incorrect tax amounts. If done correctly and promptly, businesses can avoid heavy penalties during tax audits.
Regulations regarding the deadline and conditions for submitting supplementary declarations.
Based on Tax Administration Law No. 38/2019/QH14 And the amendments and supplements (effective from January 1, 2025) stipulate the following regarding supplementary declarations:
Deadline for submitting supplementary tax returns electronically.
Taxpayers have the right to file supplementary tax returns within 10 years from the deadline for filing the return for the tax period in which the error occurred.
Note: From July 1st, 2026, this term will be reduced to 5 years.
Deadline for submitting original declarations:
- Monthly tax payment: No later than the 20th of the following month.
- Quarterly tax: No later than the last day of the first month of the following quarter.
- Annual tax settlement: No later than the last day of the 3rd month (for businesses) or the 4th month (for individuals settling their own taxes) from the end of the calendar year.
Conditions for submitting supplementary tax returns electronically.
The supplementary filing must be completed before the tax authority or competent authority announces a decision to conduct an inspection or audit at the taxpayer's premises. If the file is outside the scope or period of the inspection, the taxpayer is still allowed to file a supplementary declaration.
Documents to prepare
To ensure a smooth process for filing supplementary tax returns electronically, you need to prepare the following:
- Login account for the electronic tax system at the tax portal.
- The digital signature (USB Token) is still valid.
- Required documents: Supplementary declaration form (Form 01/KHBS), Explanation of supplementary declaration form (Form 01-1/KHBS), and invoices, supporting documents, and accounting records related to the adjustments.
- Use the latest version of the HTKK tax declaration software to avoid form errors.
Procedure for filing supplementary tax returns electronically.
Before starting the process on the system, taxpayers need to review the original tax return, accurately identify the erroneous items, and prepare all relevant documents. Once ready, you can proceed with filing a supplementary tax return electronically by following the detailed steps below:
Step 1: Log in to the system
Access the e-Tax portal at:
- For businesses: thuedientu.gdt.gov.vn
- For individuals: canhan.gdt.gov.vn
Then log in using your tax identification number and password.
Step 2: Select the declaration form that needs to be supplemented.
In the menu, select “Tax Filing”, then “Online Filing”, and then select “Supplementary Tax Return”.
Afterward:
- Select the type of tax that needs adjustment: VAT, personal income tax, corporate income tax, etc.
- The correct tax period was selected incorrectly.
- Select the original declaration form that was previously submitted.
Step 3: Enter the adjusted data.
The system will display the original form again. You need:
- Correct the incorrect criteria.
- Enter the correct adjusted figures.
- Clearly state the reason for the supplementary declaration, for example, omitting input invoices, incorrectly declaring output revenue, or adjusting deductible expenses.
If you have supporting documents, please upload them:
- Minutes of explanation.
- Adjustment invoice.
- Detailed list.
Step 4: Fill out form 01/KHBS
After re-entering the data, the system will automatically generate:
- Supplementary declaration form.
- Explanation of discrepancies 01/KHBS.
You need to check carefully:
- Tax amounts increase or decrease.
- Difference between the old and new tax returns.
- Late payment penalties may apply if there is an increase in the amount of tax payable.
Step 5: Digitally sign and submit the application.
Select “Sign and Submit”, then plug in your USB Token to electronically sign.
After successful submission, the system will display a notification acknowledging receipt of the application. Please download and save it:
- Submission successful notification.
- PDF/XML file of the supplementary declaration form.
- Form 01/KHBS has been signed.
What if filing an amended tax return increases the amount of tax payable?
When filing an amended tax return results in an increase in the amount of tax payable, you need to pay it immediately:
- The remaining tax amount.
- Late payment penalties are calculated from the deadline for submitting the original declaration to the actual date of submission.
Late payment penalties are currently calculated at 0.031 TP3T/day on the amount of tax overdue.
For example: If the additional tax increases your tax by 10 million VND and you pay 30 days late, the late payment penalty will be:
|
Late payment penalty = 10,000,000 x 0.03% = 90,000 VND |
Therefore, an additional late payment fee of 90,000 VND needs to be paid.
Some common errors when filing supplementary tax returns electronically.
The following are common mistakes that businesses and individuals often make when filing supplementary tax returns electronically. Early identification will help you avoid having your application rejected, incurring late payment penalties, or having to make multiple adjustments.
- Incorrect tax period selected.
- Incorrect tax type was declared in the supplementary declaration.
- No explanatory statement or adjustment invoice is attached.
- Using an older version of HTKK software causes form 01/KHBS to display incorrectly.
- They only submitted the supplementary tax return but forgot to pay the difference in tax and late payment penalties.
- The digital signature failed because the token has expired or the plugin is not installed in your browser.
Important notes when filing supplementary tax returns electronically.
However, in order for the supplementary tax return to be accepted by the tax authorities and to avoid unnecessary risks, taxpayers need to pay special attention to the following issues:
- Always compare the old and new tax returns before submitting them.
- Keep all electronic documents and notifications for future explanations.
- If a business is preparing for an inspection, it needs to submit the supplementary declaration as soon as possible.
- From July 1st, 2026, the deadline for filing supplementary tax returns is only 5 years, so businesses need to review any previous tax returns with errors as soon as possible.
If a business does not have a dedicated accounting department or needs assistance reviewing supplementary tax returns, the business can refer to the following: full accounting service To receive advice, data processing, and minimize tax risks.
Conclude
Filing supplementary tax returns electronically is not only a solution for correcting errors after filing the return, but also a crucial step in helping businesses proactively comply with tax laws, minimize penalties, and reduce risks during audits and inspections. Complying with deadlines, using the correct forms, and providing complete explanatory documents will ensure a quick and smooth adjustment process.
In cases where businesses encounter difficulties in determining figures, preparing form 01/KHBS, or handling arising tax discrepancies, consulting with a reputable tax, accounting, and auditing firm like MAN – Master Accountant Network is recommended for support.
Contact information MAN – Master Accountant Network
- Address: No. 19A, Street 43, Tan Thuan Ward, Ho Chi Minh City
- Mobile/Zalo: 0903 963 163 – 0903 428 622
- Email: man@man.net.vn
Content production by: Mr. Le Hoang Tuyen – Founder & CEO MAN – Master Accountant Network, Vietnamese CPA Auditor with over 30 years of experience in Accounting, Auditing and Financial Consulting.
Frequently Asked Questions about Filing Supplementary Tax Returns on the Electronic Tax System
Not all cases of supplementary tax declarations are subject to penalties. If taxpayers discover errors themselves and make the supplementary declaration before the tax authorities announce an inspection or audit decision, they are usually not penalized for incorrect declarations. However, if the supplementary declaration increases the amount of tax payable, the business must still pay the outstanding tax amount and a late payment penalty of 0.031 TP3T/day calculated on the difference.
Yes. Taxpayers are allowed to file multiple supplementary declarations for the same tax period if they continue to discover errors. However, each subsequent declaration must be based on the adjusted data from the most recent declaration, not reverting to the data from the original declaration.
Taxpayers are only allowed to file supplementary declarations before the tax authorities announce a decision to conduct an inspection or audit at their premises. If the decision has already been announced, businesses are only allowed to make adjustments to items or tax periods that are not within the scope of the inspection.
Yes. When submitting a supplementary declaration, the system will require you to resubmit the entire declaration for the period in which the error occurred. The correct items will remain unchanged, while the incorrect items will be adjusted. You must also submit Form 01/KHBS to explain the difference.
If the supplement reduces the amount of tax payable or increases the amount of tax deductible, the business will not be charged late payment penalties. The difference will be offset against the next period or a tax refund will be requested if the conditions are met as stipulated.
This error usually occurs when businesses mistakenly select the "Submit New Tax Return" function instead of the "Submit Supplementary Tax Return" function, or select the wrong tax period. Please go back to the "Submit Supplementary Tax Return" section, select the correct period that was previously submitted, and then make the correction.
No. Form 01/KHBS is a mandatory document to explain the reasons and figures for discrepancies between the old and supplementary tax returns. Without this form, the tax authorities may reject the application or request a resubmission.
Yes. HTKK is just a tool for preparing tax declarations. After exporting the XML file from HTKK, businesses still have to log into the e-Tax portal to upload the file, digitally sign it, and officially send it to the tax authorities.
Currently, taxpayers are allowed to file supplementary returns within 10 years from the filing deadline for the tax period with errors. However, from July 1, 2026, this period will be reduced to 5 years, so businesses should review previous periods early to avoid losing the right to make adjustments. Will I be penalized for submitting a supplementary declaration?
Is it possible to file multiple supplementary tax returns for the same tax period?
After the tax authorities send a notice of inspection, is it still possible to file a supplementary declaration?
Do I need to resubmit the entire declaration form when filing an amended declaration?
What happens if a tax return filed as a supplement results in a reduction of the tax payable?
What should be done if the system reports that a declaration form already exists when submitting supplementary documents?
Will my application be accepted if I don't submit form 01/KHBS?
If I've already filed a supplementary tax return on the HTKK system, do I need to do it again on the electronic tax portal?
What is the current deadline for submitting supplementary declarations?
