The declaration of Indicators 37 and 38 on the VAT tax return has undergone significant changes effective from July 1, 2026. Circular 89/2026/TT-BTCThe new Form 01/GTGT not only uses these two indicators for the amount of deductible VAT adjusted upwards or downwards from supplementary declarations as before, but also stipulates many more situations for direct declaration at the period of discovery or the period in which the obligation arises.
This change is particularly noteworthy for businesses that file VAT returns monthly. If accountants continue to apply the processing method of form 01/GTGT... Circular 80/2021/TT-BTC For periods from July 2026 onwards, the input VAT figures and the amount of VAT deductible and carried forward to the next period may be inaccurately reflected.
Summary of key points regarding the declaration of indicators 37 and 38.
The declaration of indicators 37 and 38 is used to adjust the remaining deductible VAT from previous periods on form 01/GTGT.
- Indicator [37]: Adjusting down the amount of VAT that can still be deducted from previous periods.
- Indicator [38]: Adjusting the amount of VAT that can still be deducted from previous periods.
- From July 1st, 2026, the use of these two indicators will be expanded according to Circular 89/2026/TT-BTC.
- There are cases where declarations are made at the period when the error is discovered, the period when the payment obligation arises, or the period when the adjusted or replacement invoice is received, instead of relying solely on supplementary declaration documents as previously understood.
What do items 37 and 38 on the VAT tax return mean?
First, it is necessary to distinguish the nature of these two indicators from the indicators reflecting output VAT. Indicators [37] and [38] are in the group of adjusting the amount of VAT that is still deductible from previous periods.
Simply put:
| Target | Content | Impact |
| [37] | Adjusting the remaining deductible VAT from previous periods downwards. | Reduce the amount of tax deductible. |
| [38] | Adjusting the deductible VAT from previous periods upwards. | Increase the amount of tax deductible. |
Therefore, accountants should not focus solely on whether the amount on the invoice is "increasing" or "decreasing." It is necessary to determine the actual amount of deductible input VAT that needs adjustment.
This is also a common point of confusion when businesses process adjustment invoices or discover incorrect input invoices.
Why will the method of declaring indicators 37 and 38 change from July 2026?
From July 1st, 2026, Circular 89/2026/TT-BTC will apply the new Form 01/GTGT. According to the published regulations, Circular 80/2021/TT-BTC is repealed from this date, and the new Form 01/GTGT will replace the previous one.
According to previous instructions, indicators [37] and [38] are mainly understood as the amount of deductible tax adjusted upwards or downwards in indicator II on the supplementary declaration. In case the tax authority or competent authority has a conclusion or decision on handling, the adjusted amount is included in the tax declaration file of the period in which the conclusion or decision is received.
From 01/07/2026, the scope of use cases [37] and [38] are specified more clearly. This is why accountants need to distinguish between the base period, the period of error detection, the period of payment obligation arising, and the period of receipt of adjustment or replacement invoices.
When should indicators 37 and 38 be declared monthly?
For businesses that file VAT returns monthly, it is necessary to identify the correct month for which the regulations require data to be included in the return.
Case 1: Purchase of goods with deferred payment or installment plan from 5 million VND.
This is one of the changes that needs special attention from July 1, 2026.
For goods and services purchased on deferred payment or installment plans with a value of 5 million VND or more, if, at the time the payment obligation arises according to the contract, the business does not have the required non-cash payment documents, the corresponding input VAT must be adjusted downwards.
This tax amount is included in item [37] of the tax period in which the payment obligation arises according to the contract or contract addendum. No supplementary tax return filing is required for this reason alone.
For example: Company A purchased a shipment worth 100 million VND, with VAT of 10 million VND, using a deferred payment method. By September 2026, the payment obligation arose according to the contract, but the company did not yet have non-cash payment documentation as required for deduction.
At that time, the accountant needs to review the input VAT that is being deducted and make adjustments to the ineligible tax amount in [37] September 2026 according to regulations.
When can it be re-declared in Indicator 38?
If, after the downward adjustment, the business makes payment and has non-cash payment documents that meet the conditions, the input VAT amount eligible for deduction can be declared in item [38] of the tax period with non-cash payment documents.
For example: The tax amount of VND 10 million was adjusted down in [37] September 2026. By October 2026 the enterprise paid in accordance with regulations and had valid documents.
Then, if the conditions for deduction are fully met, the accountant can include the eligible tax portion in [38] October 2026.
The important point is that the entire tax amount should not be automatically included [38]. Accountants must check the payment documents and the relevant deduction conditions before doing so.
How should input invoices with incorrect or missing information be declared in items 37 and 38?
This is a high-risk business group because the handling procedures from July 1, 2026, differ from the previously common understanding.
According to the instructions for the new form 01/GTGT, when taxpayers discover that the declared and deducted input VAT is incorrect or missing, if the adjustment in the period in which the error occurs only reduces the amount of tax payable or only increases or decreases the amount of VAT that can be deducted and carried forward to the next period, the adjustment amount is included in [37] or [38] of the month or quarter in which the error is discovered, and no supplementary declaration of the original period is required in cases falling under this regulation.
This is a point that accountants need to check carefully before preparing the documents.
The principle of "always filing a supplementary invoice in the month the invoice is incorrect" should not be applied mechanically. The nature of the error and its impact on tax obligations must be considered.
Example of downward adjustment
In July 2026, the business declared an input invoice with deductible VAT of 8 million VND.
By September 2026, the accountant discovered that this invoice did not qualify for a full tax deduction.
If the case falls under the regulations allowing adjustment at the time of discovery, the accountant makes a downward adjustment of 8 million VND at [37] September 2026.
Example of upward adjustment
Conversely, the business discovered that it had previously overlooked a portion of eligible input VAT, and that case falls within the scope of adjustment in the period of discovery.
If the additional deductible tax is 5 million dong, the accountant puts 5 million dong into [38] the month in which the error is discovered.
It's not just about entering the amounts into the software. Documentation proving the source of the data must be kept with the accounting documents for explanation when needed.
Do adjustment invoices and replacement invoices need to be declared additionally?
From July 1st, 2026, this is also a case that requires special attention.
According to the guidelines for form 01/GTGT under Circular 89/2026/TT-BTC, when the buyer receives an adjusted invoice or a replacement invoice in the cases stipulated below... Clause 5, Article 10 of Circular 91/2026/TT-BTC, the adjusted VAT amount is declared in [37] or [38] of the tax period receiving the adjusted invoice, replacement invoice, instead of making supplementary declarations of the previous period in the old way.
The cases mentioned include situations such as product returns, trade discounts, or post-settlement adjustments in accordance with current guidelines.
Therefore, when receiving an adjustment invoice, the accountant should follow this procedure:
- Identify the original invoice.
- Identify the reason for adjustment or replacement.
- Check the contents of the new invoice.
- Determine the increase or decrease in input VAT.
- Determine the filing period as prescribed.
- Enter the data into [37] or [38] if applicable.
- Retain original invoices, adjustment or replacement invoices, and related records.
See more: NPrinciples for handling erroneous invoices according to Circular 91/2026.
Does switching from the deduction method to the direct method relate to indicator 37?
Have. According to the instructions of the new form 01/GTGT, when taxpayers switch from the VAT calculation method using the deduction method to the direct method on revenue, the input VAT that has not been fully deducted must be adjusted down in item [37] of the last tax period before the conversion. In this case, supplementary declaration is not required just because of the change in tax calculation method.
For example: The business is currently using the deduction method, and at the end of the period before switching to the direct method, there is still 70 million VND of uncredited input VAT.
According to the new guidelines, businesses must process this tax portion at [37] the last tax period before conversion.
This is a situation that needs to be addressed by the accountant immediately during the transition period to avoid the continued existence of a deductible VAT balance that is inconsistent with the new tax calculation method.
How do indicators 37 and 38 differ from supplementary declarations?
This is the most important step before entering data. Below is a comparison table distinguishing between indicators [37] and [38].
| Situation | How to handle it |
| Adjusting the amount of deductible VAT downwards. | Indicator [37] |
| Adjusting upwards the amount of deductible VAT. | Indicator [38] |
| Goods purchased on deferred payment or installment plans exceeding 5 million VND and for which non-cash payment documentation is not yet available by the due date. | Indicator [37] at the time the payment obligation arises |
| Then there is a valid payment document. | Indicator [38] at the period with supporting documents |
| Input VAT errors that fall under the cases permitted for adjustment at the time of discovery. | Indicator [37] or [38] depending on the detection period |
| Receive adjusted or replacement invoices in the specified cases. | Indicator [37] or [38] depending on the billing period |
| Switching from deduction to direct | Indicator [37] last period before conversion |
| Other cases of supplementary declaration | Process according to the regulations on supplementary declarations. |
The table above is for guidance only. Before making actual declarations, businesses need to compare their specific case with Article 12 of Decree 252/2026/ND-CP and Appendix II of Circular 89/2026/TT-BTC.
Should all errors in input VAT be included in indicators 37 and 38?
Are not. This is one of the mistakes accountants often make when applying new regulations.
The detection of errors does not mean that the amount is automatically included [37] or [38]. First, it is necessary to determine which type of error it is and how it affects the amount of tax payable, the amount of tax deductible carried forward to the next period, or the amount of tax requested for refund.
According to the guidelines on supplementary declarations in Circular 89/2026/TT-BTC, there are cases where supplementary declarations must still be filed for the tax period with errors. For example, when a supplementary declaration reduces the amount of VAT payable or results in an increase in the amount of VAT payable, the handling will differ from cases involving only erroneous input VAT that is subject to adjustment in the period in which the error is discovered.
Therefore, before entering [37] or [38], the accountant should answer three questions:
- What type of error is it?
- Does it affect tax obligations or only the amount of tax that can be carried forward as a deductible tax?
- Do current regulations require processing at the time of origin or the time of discovery?
How to declare items 37 and 38 on the monthly VAT return.
Businesses can follow the following inspection procedure.
Step 1: Determine the filing period
Determine which month the business is filing the declaration. Do not default to the month of invoice issuance as the declaration period [37] or [38].
Step 2: Identify the cause of the adjustment.
Classification of causes:
- Deferred payment, installment payment.
- Incorrect or missing input invoices.
- Adjustment invoice.
- Replacement invoice.
- Change the tax calculation method.
- Other adjustments may be made as per regulations.
Step 3: Determine whether it's increasing or decreasing.
If reducing the amount of deductible VAT is possible, please consider it. [37].
If it increases the amount of deductible VAT, then consider it. [38].
Step 4: Determine the correct period
This is the step where mistakes are most likely to occur.
Depending on the circumstances, the filing period may be:
- The period in which the payment obligation arises.
- This period has non-cash payment documentation.
- Error detection period.
- Period for receiving adjusted or replacement invoices.
- The last tax period before the method change.
Step 5: Compare the remaining deductible tax amount.
After entering [37] or [38], it is necessary to recheck the aggregate indicator of the VAT amount that is still deductible and carried forward to the next period.
It is not advisable to check only the amounts entered at [37] or [38]. The ultimate goal is to ensure that the entire declaration accurately reflects the enterprise's tax obligations.
Case study: Businesses incorrectly declare input VAT.
Company A declares VAT on a monthly basis. In July 2026, the company declared input VAT of VND 120 million that was eligible for deduction.
By September 2026, the accounting department reviewed the data and discovered that 12 million VND of input VAT was incorrectly declared. Assuming the error falls under the category of errors that can be addressed at the time of discovery, and the adjustment only changes the amount of deductible VAT carried forward to the next period.
In that case, the accountant should not automatically revert to the old method of correction simply because the invoice was generated in July.
According to the new regulations, if the conditions of the above case are met, the tax adjustment amount of 12 million VND is included in [37] of the September 2026 declaration, which is the period in which the error was detected.
After receiving the data, the business checks the remaining VAT amount that can be deducted and carried forward to the next period.
If, before the adjustment, the amount of deductible tax carried forward to the next period was 80 million VND, then in principle, the impact of the 12 million VND adjustment alone would reduce this amount to 68 million VND, assuming no other fluctuations occur during the period.
This case study shows that the key is not the process of entering numbers in the HTKK software. The crucial point is correctly identifying the legal basis and the correct declaration period.
What records do businesses need to keep when declaring indicators 37 and 38?
When adjustments are needed, businesses should prepare documentation that can explain all cash flows and tax amounts.
Depending on the case, the file may include:
- Input VAT invoice.
- Sales contract.
- Contract addendum.
- Minutes of debt reconciliation.
- Payment voucher.
- Adjustment invoice or replacement invoice.
- Return or trade discount records.
- Supplementary documents should be submitted if required.
- The spreadsheet determines the tax adjustment amount.
- VAT tax return for the relevant period.
A good application should answer this question: Why do businesses decrease or increase the amount of deductible VAT in this category?
If the source of the data cannot be explained, the risk is not just limited to a single number on the tax return but can extend to determining the eligibility for input VAT deduction.
Expert opinion: The biggest risk lies in correctly identifying the period.
From the perspective of MAN – Master Accountant Network, the most difficult problem when handling [37] and [38] is not operating on the software but correctly classifying the legal situation before filing.
Specifically from July 2026, businesses must shift from a "correct errors in the current period" mindset to a mindset of examining the nature of errors, their impact on tax obligations, and regulations regarding the declaration period. Circular 89/2026/TT-BTC has added specific cases related to deferred payments, installment payments, input tax errors, adjustment invoices, replacement invoices, and changes in tax calculation methods.
MAN – Master Accountant Network, with over 30 years of practical experience, notes that businesses should establish an independent audit before filing their tax return. The person preparing the return needs to determine the basis, and the auditor needs to verify the filing period, the amount, and the supporting documents.
This control method is particularly useful for businesses with numerous input invoices, deferred payment transactions, frequent invoice adjustments, or regular purchasing activities.
Documents to note when declaring indicators 37 and 38.
Below is a summary of the documents to note when filling out items 37 and 38 on the VAT tax return.
| Document | Relevant time | Points to note |
| Circular 89/2026/TT-BTC | From July 1, 2026 | New form 01/GTGT regulations and instructions on how to fill it out [37], [38] |
| Circular 91/2026/TT-BTC | From July 1, 2026 | Regulations related to adjustment invoices and replacement invoices. |
| Decree 252/2026/ND-CP | Effective July 1, 2026 | There are regulations related to handling VAT declarations and adjustments. |
| Circular 80/2021/TT-BTC | Regulations prior to July 1, 2026 | This should be distinguished from the regulations applicable from July 1, 2026. |
Important Note: According to updated legal sources, Circular 80/2021/TT-BTC will be repealed from July 1, 2026, as per the transitional provisions of Circular 89/2026/TT-BTC. Therefore, when processing tax declarations arising from July 2026 onwards, accountants should prioritize checking the new forms and instructions.
Conclude
The declaration of indicators 37 and 38 from July 2026 needs to be done according to the new regulations of Circular 89/2026/TT-BTC. Indicator [37] reflects downward adjustment, [38] reflects upward adjustment of the VAT amount still deductible from previous periods. A point to note is that the new regulations have expanded and more clearly classified the declaration cases, including delayed payment, installment payment, input VAT errors, adjusted or replacement invoices and conversion of tax calculation methods.
For businesses with numerous transactions and frequent adjustments, verifying the correct basis, period, and amount of tax before filing tax returns is crucial for effective tax risk management. MAN – Master Accountant Network, with a team of experts boasting over 30 years of experience and practical knowledge of tax risk management in Vietnam, provides solutions. full accounting service, tax accounting services, Chief Accountant Rental Service and accounting consulting servicesThis includes assisting businesses in reviewing documents, correcting errors, and controlling tax obligations in accordance with current regulations.
Contact MAN – Master Accountant Network For free support and advice!
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Responsible for production and professional content review by: Mr. Le Hoang Tuyen – Founder & CEO of MAN – Master Accountant NetworkHe is a CPA Vietnam auditor with over 30 years of in-depth experience in accounting, auditing, taxation, and corporate legal consulting.
Frequently Asked Questions about how to fill out items 37 and 38 on the tax return form.
What is indicator 37 used for?
Indicator [37] is used to adjust down the amount of VAT that can still be deducted from previous periods in cases under applicable regulations.
What is indicator 38 used for?
Indicator [38] is used to adjust the amount of VAT that can still be deducted from previous periods in cases where declaration is allowed.
From July 2026 onwards, will errors in input VAT always require supplementary declarations in the base period?
Not in all cases. With some input VAT errors within the scope of the new regulations, the adjustment amount is included in [37] or [38] of the period in which the error is detected if the conditions are met. Other cases still require supplementary declaration as prescribed.
How should goods purchased on deferred payment or installment plans without non-cash payment documentation be declared?
If goods and services are subject to the requirement of non-cash payment documents and the payment obligation is not met by the payment period, the corresponding input VAT is adjusted downward at [37] of the payment obligation period. When a valid payment document is available, the eligible amount can be declared upwards at [38] of the period in which the document is available.
If I receive an adjusted or replacement invoice, do I need to amend the previous tax return?
Not all cases require correction in the previous period. For cases under the guidance of the new form 01/GTGT, the buyer declares the adjustment at [37] or [38] of the period in which the adjustment or replacement invoice is received.
