Thailand Tax Invoice Requirements: 13 Mandatory Fields Guide

Thai tax invoices must contain 13 mandatory fields defined under Revenue Code Section 86/4. These fields include the issuer's name, registered address, and taxpayer identification number; the purchaser's corresponding details; a sequential serial number; itemized descriptions with VAT calculated and displayed separately from the net value; and the date of issuance. All invoices must be prepared in Thai unless the Director-General of the Revenue Department has granted explicit approval for a foreign language.

For AP teams and finance professionals on the receiving end of these invoices, the stakes are straightforward: an incomplete or non-compliant tax invoice cannot be used to claim input tax credit. A missing field, an incorrect TIN, or a failure to separate VAT from the item value does not just create an administrative headache. It directly reduces the receiving company's recoverable tax position, turning what should be a neutral transaction cost into an actual expense.

This guide provides a complete reference for Thailand tax invoice requirements, covering every mandatory field, all three invoice types, language and currency rules, and the compliance obligations that protect input tax credit eligibility for AP departments and international accounting firms processing Thai invoices.

How Thailand's VAT System Shapes Tax Invoice Requirements

Thailand operates a value-added tax (VAT) system administered by the Thai Revenue Department, and every tax invoice requirement traces back to this framework. Understanding the VAT structure is essential before examining the specific fields each invoice must contain.

The statutory VAT rate under Thailand's Revenue Code is 10%, but a Royal Decree has reduced the effective rate to 7%, a reduction maintained continuously since 1997 and currently extended through September 2026, as documented in PwC's tax summary for Thailand. This 7% rate applies to most goods and services, and it is the rate you will see on virtually every Thai tax invoice your AP team processes.

VAT registration is mandatory for any business operating in Thailand with annual revenue exceeding THB 1.8 million (roughly THB 300,000 per month). Businesses below this threshold may register voluntarily, but once registered, the full obligations apply equally. For AP teams at foreign companies, the practical implication is straightforward: any Thai supplier large enough to do meaningful business with your organization is almost certainly VAT-registered and required to issue compliant tax invoices.

That obligation is triggered at a specific moment. VAT-registered businesses must issue a tax invoice upon delivery of goods or upon receipt of payment for services, whichever is applicable. A supplier cannot defer issuance or bundle multiple transactions into a single retroactive invoice. The timing is prescribed by the Revenue Code.

These invoices feed directly into Thailand's monthly VAT reporting cycle. Every VAT-registered business must file a PP30 VAT return by the 15th of the month following the tax period, even in months with zero sales. This monthly cadence creates a regular, recurring need for invoice verification on both the seller and buyer sides. If your organization claims input VAT credits on Thai purchases, the invoices supporting those claims must withstand scrutiny during PP30 reconciliation and any subsequent audit.

Every tax invoice issued under this system must contain 13 specific mandatory fields prescribed by Revenue Code Section 86/4. A missing or incorrect field does not merely create an administrative inconvenience. It can disqualify the invoice for input tax credit purposes entirely.

Thailand is also progressively implementing an e-tax invoice and e-receipt system that introduces additional digital requirements beyond the standard tax invoice rules covered in this guide.

All 13 Mandatory Fields Under Revenue Code Section 86/4

Section 86/4 of the Thai Revenue Code specifies 13 mandatory elements that every full tax invoice must contain. When you receive a Thai tax invoice, verify each of these fields before processing it for payment or claiming input tax credit. An invoice missing any single element may be rejected by the Revenue Department, leaving your company unable to recover the 7% VAT paid.

Here is the complete list of required fields, explained from the perspective of the AP team verifying incoming invoices.

1. The words "Tax Invoice" (ใบกำกับภาษี) prominently displayed

The document must be clearly labeled as a tax invoice in both Thai (ใบกำกับภาษี) and, in practice, often in English as well. This label typically appears at the top of the document. If you receive a document titled only as "Invoice" or "Receipt" without this designation, it does not qualify as a valid tax invoice under Thai law.

2. Name of the VAT registrant issuing the invoice

Verify that the full legal name of the supplier or service provider, as registered for VAT, appears on the invoice. Cross-reference this name against your vendor master records and the Revenue Department's VAT registrant database to confirm the entity is a legitimate, active registrant.

3. Address of the VAT registrant

Check that the registered business address of the issuing party is printed on the invoice and matches the address on file with the Revenue Department. Discrepancies between the stated address and the official registration can invalidate the invoice for input tax credit purposes. If a supplier has recently relocated, confirm address accuracy before processing.

4. Taxpayer Identification Number (TIN) of the issuer

The 13-digit TIN of the VAT registrant issuing the invoice is required. This number serves as the primary identifier for tax reporting. Verify that the TIN corresponds to the named entity by checking it against the Revenue Department's online lookup tool.

5. Name of the purchaser

Your company's full legal name, as registered for VAT in Thailand, must appear on the invoice as the purchaser. Invoices addressed to an incorrect legal entity, a trade name, or an abbreviated version of your company name may be challenged during a tax audit. Maintain a list of your exact legal name in Thai and English, and distribute it to suppliers to prevent this common error.

6. Address of the purchaser

Your company's registered address must be stated accurately. If your organization operates from multiple locations in Thailand, confirm that the address on the invoice matches the branch or office that actually received the goods or services. After any office relocation, proactively notify all recurring suppliers of the updated address to avoid rejected invoices.

7. Serial number of the tax invoice (and book number if applicable)

Every tax invoice must carry a unique serial number. Some businesses also use a book number system for internal tracking. The serial number establishes the invoice's place in the issuer's sequential records and is critical for audit trail purposes. Duplicate or missing serial numbers are a red flag during Revenue Department audits.

8. Description, type, or category of goods or services

The invoice must include a clear description of what was supplied. Vague entries such as "services rendered" or "miscellaneous goods" may not satisfy the Revenue Department's requirements. Verify that the description matches your purchase order and accurately reflects the transaction. Where descriptions are insufficient, request an amended invoice before processing payment.

9. Value of goods or services

The total value of the goods or services before VAT must be stated. This figure should align with your purchase agreement or contract terms. Any discrepancy between the invoiced value and the agreed price needs resolution before you process the payment.

10. VAT amount (clearly separated from value)

The VAT charged must be shown as a separate line item, distinct from the pre-tax value. Under the standard Thailand tax invoice format, the 7% VAT cannot be bundled into the total without separate disclosure. If the VAT amount is embedded in the total without being broken out, the invoice does not meet the mandatory field requirements.

11. Date of issuance

The date the tax invoice was issued must be printed on the document. This date determines the tax period in which you can claim the input tax credit. Under Thai tax invoice rules, you generally must claim the credit in the month corresponding to the invoice date, so late-arriving invoices require careful attention to filing deadlines.

12. Head office or branch designation

This is one of the most commonly overlooked Thailand tax invoice mandatory fields. The invoice must clearly state whether it was issued by the supplier's "Head Office" (สำนักงานใหญ่) or by a specific branch, identified by its branch number (e.g., "Branch 00001"). Similarly, the purchaser side of the invoice should reflect your correct head office or branch designation. The branch number must match the number registered with the Revenue Department. Invoices that omit this field or list it incorrectly are a frequent cause of input tax credit rejections. If you notice this field is missing on invoices from a recurring supplier, flag it immediately and request corrected documents.

13. Any additional particulars prescribed by the Director-General

The Director-General of the Revenue Department has the authority to require additional information on tax invoices through departmental notifications. These supplementary requirements change over time and may apply to specific industries or transaction types. Stay current with Revenue Department announcements, or work with a local tax advisor, to ensure invoices you accept reflect any additional mandated particulars.

The 13-field requirement described above applies specifically to full tax invoices. However, Thailand also recognizes abbreviated tax invoices and substitute tax invoices, each carrying different field requirements and different eligibility rules for input tax credit claims.

Full, Abbreviated, and Substitute Tax Invoices Compared

Thai tax law recognizes three distinct types of tax invoices, each with different field requirements and different implications for input VAT recovery. For AP teams processing invoices from Thai suppliers, correctly identifying the invoice type determines whether you can claim an input tax credit on the transaction.

Full tax invoice is the standard document for B2B transactions in Thailand. It contains all 13 mandatory fields prescribed under Revenue Code Section 86/4, including the seller's and buyer's names, addresses, taxpayer identification numbers, and a complete itemized breakdown of goods or services with VAT calculated separately. A full tax invoice is the only type that entitles the purchaser to claim input VAT credit. For any business seeking to offset VAT paid on purchases against VAT collected on sales, this is the document that must be on file.

Abbreviated tax invoice is a reduced-format document that approved retail businesses may issue. To qualify, the seller must have received cash register machine approval from the Thai Revenue Department. Abbreviated tax invoices apply to retail sales of THB 1,000 or less and contain fewer fields than a full tax invoice, typically omitting the buyer's name, address, and taxpayer identification number. The critical distinction for AP teams: abbreviated tax invoices cannot be used to claim input VAT credit. They exist as a compliance convenience for high-volume retail sellers, not as a valid basis for B2B tax recovery.

Substitute tax invoice serves as a replacement document when the original tax invoice has been lost, damaged, or destroyed. The substitute must reference the original invoice details, including the original invoice number and date of issuance, and be clearly marked as a substitute. The Thai Revenue Department requires that substitute tax invoices reproduce the same information as the original so that they can support the same input tax credit claim the original would have.

If a Thai supplier provides an abbreviated tax invoice for a B2B purchase, always request a full tax invoice instead. Confirm all 13 mandatory fields are present before processing payment.

Language and Currency Rules for Thai Tax Invoices

Thailand's Revenue Department mandates that tax invoices be composed in the Thai language, using Thai Baht as the currency denomination and Thai or Arabic numerals for all figures. This default rule applies to every VAT-registered business operating within the country, regardless of the parent company's nationality or the transaction's cross-border nature.

Foreign companies that need to issue tax invoices in a language other than Thai must obtain prior written approval from the Director-General of the Revenue Department. This is not an automatic entitlement. The process requires a formal application, and invoices issued in a foreign language without this approval risk being treated as invalid for VAT purposes. For foreign enterprises operating in Thailand through a branch or representative office, there is a practical middle ground: they may compose invoices in a foreign language, but each invoice must include an attached Thai translation that covers all mandatory fields.

Dual-currency display is required whenever a transaction involves foreign currency. The tax invoice must show both the original foreign currency amount and the equivalent value in Thai Baht. The exchange rate used for this conversion must align with the rates published by the Bank of Thailand on the date of the transaction. Discrepancies between the applied rate and the official reference rate can trigger audit queries, so AP teams processing these invoices should verify the conversion independently against Bank of Thailand published rates.

From the AP and receiver perspective, Thailand invoice language requirements create a specific operational challenge. When your team receives a Thai tax invoice composed entirely in Thai script, the obligation to extract and verify all 13 mandatory fields remains unchanged. Knowing the standard field sequence and document layout becomes critical for compliance verification, even when individual characters are not readable to non-Thai speakers. Many AP departments serving foreign companies operating in Thailand address this by maintaining reference templates that map field positions to their English equivalents, allowing consistent verification without full Thai language proficiency.

One additional categorization challenge remains: distinguishing tax invoices from receipts, which serve fundamentally different purposes under Thai tax law.

Tax Invoice vs Receipt: What AP Teams Need to Know

Thai suppliers issue two distinct document types that AP teams regularly encounter, and confusing them carries a direct financial cost. Understanding the legal function of each document is essential for correct categorization and accurate VAT recovery.

A tax invoice (ใบกำกับภาษี) is a statutory document issued by a VAT-registered business upon delivery of goods or upon receipt of payment for services. It must contain all 13 mandatory fields prescribed under Revenue Code Section 86/4 and display the words "Tax Invoice" or "ใบกำกับภาษี" prominently. Only a valid full tax invoice supports an input tax credit claim with the Revenue Department.

A receipt (ใบเสร็จรับเงิน), by contrast, is proof of payment issued to end consumers. It confirms that money changed hands but carries no VAT recovery function. A receipt does not support input tax credit claims under any circumstances, regardless of whether it shows a VAT amount or a supplier's tax identification number.

The practical consequence for AP teams is straightforward: processing a receipt as though it were a tax invoice means the input VAT on that transaction cannot be claimed. Over hundreds of transactions, this directly reduces the company's recoverable VAT and increases effective procurement costs. For foreign companies operating in Thailand with high transaction volumes, the cumulative impact on cash flow can be substantial.

The decision rule AP staff should apply is clear. If a document does not display the words "Tax Invoice" (ใบกำกับภาษี) and does not contain all 13 mandatory fields, it is not a valid tax invoice for input tax credit purposes. This holds true regardless of what other information the document contains, how professional it looks, or whether a VAT amount appears on its face. Understanding the key differences between invoices and receipts is a foundational skill for any AP team handling Thai supplier documents.

One common variation worth noting: many Thai businesses issue a combined "Tax Invoice/Receipt" (ใบกำกับภาษี/ใบเสร็จรับเงิน) document that serves both as proof of payment and as a valid tax invoice. This combined format is fully acceptable for input tax credit purposes, provided all 13 mandatory fields are present and correctly completed. AP teams should treat these combined documents as valid tax invoices after verifying field completeness.

When discrepancies arise between the agreed price and the invoiced amount, Thai tax law requires formal corrective documents: debit notes and credit notes.

Debit Notes and Credit Notes Under Thai VAT

When the original tax invoice amount no longer reflects the actual transaction value, Thai VAT law requires a formal adjustment through either a debit note or a credit note. These are not optional corrections. They are legally mandated documents that directly affect both parties' VAT positions.

Debit notes are issued when the actual value of goods or services exceeds the amount on the original tax invoice. This happens when the initial price was understated, meaning additional VAT is now owed. The debit note increases the output tax liability for the supplier and increases the input tax credit for the receiver. For AP teams processing Thai supplier invoices, understanding debit notes in accounting is essential for accurate VAT reporting.

Credit notes are issued in the opposite scenario: when the actual value turns out to be less than what was stated on the original tax invoice. Common triggers include returned goods, post-sale discounts, or pricing errors that overstated the original amount. The credit note reduces the supplier's output tax and simultaneously reduces the receiver's input tax credit. Knowing how credit notes differ from invoices helps AP teams classify these documents correctly when they arrive from Thai suppliers.

Key Rules Governing Issuance

Both document types operate under strict conditions defined in the Revenue Code:

Only VAT-registered businesses can issue debit notes and credit notes. An unregistered entity cannot produce a valid adjustment document under Thai VAT law.
A tax invoice must already exist. Debit notes and credit notes are adjustment documents tied to a prior tax invoice. They cannot function as standalone billing instruments.
Timing is tightly controlled. The adjustment document must be issued in the same month as the event triggering the change, or no later than the following month. Missing this window creates compliance exposure.

What This Means for AP Teams

When your team receives a debit note from a Thai supplier, the input tax claimed on the original invoice increases. When you receive a credit note, the input tax decreases. In both cases, you must reflect the adjustment in your PP30 VAT return for the period in which you received the document.

The critical detail here is accuracy of timing. Failing to adjust input tax in the correct period does not simply defer the obligation. During a Revenue Department audit, mismatched periods between the adjustment document date and the PP30 filing create discrepancies that can trigger penalties and surcharges. AP teams should treat every debit note and credit note as a time-sensitive compliance event, not routine paperwork to batch at quarter-end.

Record Retention Requirements and Penalty Schedule

Thailand's Revenue Code requires that all tax invoices, purchase and sale records, and supporting VAT documentation be retained for a minimum of five years from the date of filing the relevant tax return. The Director-General of the Revenue Department holds authority to extend this period to seven years for specific taxpayers or industries, particularly where audit risk is elevated or complex cross-border transactions are involved.

For organizations storing records digitally, the Electronic Transactions Act imposes additional obligations. Electronic copies of tax invoices must maintain their integrity and authenticity throughout the retention period. In practice, this means digital records must be tamper-evident, time-stamped, and fully retrievable in their original format upon request by the Revenue Department. Simply scanning a paper invoice into a PDF may not satisfy these requirements unless the system can demonstrate the record has not been altered since capture.

Penalty Schedule for Tax Invoice Violations

The penalties for non-compliance with Thailand tax invoice rules are structured to escalate based on severity and intent:

Administrative penalties:

Failure to issue a tax invoice when required carries a fine of THB 2,000 per invoice. For businesses processing hundreds of transactions monthly, this adds up rapidly.
Late filing of VAT returns (Form PP30) triggers a surcharge of up to THB 2,000 per month, plus 1.5% monthly interest on unpaid tax amounts. Interest accrues from the filing deadline until the date of payment.
Incorrect or incomplete VAT returns result in a penalty of 100% of the unpaid tax amount, effectively doubling the liability.

Criminal penalties:

Intentional non-issuance of a tax invoice is treated as a criminal offense, carrying up to seven years of imprisonment and/or a fine of up to THB 200,000. This provision targets deliberate tax evasion rather than administrative errors, but the distinction underscores the seriousness Thai authorities attach to tax invoice compliance.

Input Tax Credit Implications

For AP teams on the receiving side, proper retention directly protects your ability to claim and defend input tax credits. Unused input tax from valid tax invoices can be carried forward for up to six months from the applicable tax period. If a refund is warranted, claims must be filed within three years of the relevant filing date.

During a Revenue Department audit, the burden falls on the taxpayer to produce original or authenticated copies of every tax invoice supporting an input tax credit claim. Missing, incomplete, or unverifiable invoices result in automatic disallowance of the corresponding credit, with the 100% penalty on unpaid tax potentially applied on top.

International Retention Comparison

Thailand's five-to-seven-year retention window sits in the middle range globally. For comparison, refer to a detailed breakdown of global invoice retention requirements by country across major jurisdictions. Japan requires seven years (ten for certain corporations), the EU generally mandates five to ten years depending on the member state, and the United States requires a minimum of three years from the filing date (though the IRS recommends seven). Organizations operating across multiple countries should align their retention policies to the longest applicable period rather than managing separate timelines per jurisdiction.

Organizations processing Thai-script invoices alongside documents in other languages may benefit from tools for processing multilingual invoices to ensure consistent extraction and retrieval across their document archive.

Thai Tax Invoice Verification Checklist for AP Teams

The requirements covered throughout this article distill into a step-by-step verification process for incoming Thai tax invoices. AP teams can use the following checklist as a quick reference when processing each document to protect input tax credit eligibility and maintain compliance with the Revenue Code.

1. Confirm the document type designation. The invoice must display "Tax Invoice" (ใบกำกับภาษี) on its face. A document labeled only "Receipt" (ใบเสร็จรับเงิน) does not qualify for input VAT credit claims, regardless of what financial information it contains.

2. Verify the invoice format matches your credit requirements. If your organization intends to claim input tax credit, the document must be a full tax invoice rather than an abbreviated version. Abbreviated tax invoices are valid only for retail transactions under 1,000 THB and do not support input tax credit claims by the purchaser.

3. Check all 13 mandatory fields for completeness. Confirm the presence of each required element under Section 86/4:

Issuer's name, address, and taxpayer identification number (TIN)
Purchaser's name and address
Invoice serial number
Itemized descriptions of goods or services supplied
Value of goods or services before VAT
VAT amount shown separately from the pre-tax value
Date of issuance
Head office or branch designation for both issuer and purchaser

A single missing field can invalidate the entire document for input tax credit purposes.

4. Confirm language compliance. The invoice should be in Thai. If the supplier holds Director-General approval to issue invoices in a foreign language, verify that approval is current. For invoices received from foreign enterprises, confirm that a Thai translation is attached where required by the Revenue Department.

5. Validate currency presentation on foreign transactions. For cross-border purchases or transactions denominated in foreign currency, verify that both the foreign currency amount and the Thai Baht equivalent appear on the invoice. The exchange rate used should align with Bank of Thailand reference rates for the transaction date.

6. Cross-reference any debit notes or credit notes. When you receive a debit note or credit note, confirm it references a specific, previously issued tax invoice by serial number and date. Verify that the adjustment document was issued within the required timeframe, which is the same tax period as the triggering event or the following month.

7. File and retain the invoice for the full statutory period. Store the original tax invoice for a minimum of 5 years from the relevant tax filing date. This applies to both paper and electronic records, and the Revenue Department may extend this period to 7 years by written notification.

8. Verify the expense category is creditable. Non-creditable items such as entertainment expenses cannot generate input tax credit, even when supported by a valid full tax invoice with all 13 fields present. These expenses may still be deductible for corporate income tax, but they fall outside VAT input credit recovery. Flag these categories separately during invoice processing.

Consistent application of this checklist protects input tax credit claims, reduces exposure during Revenue Department audits, and ensures accurate VAT reporting across filing periods. For organizations processing invoices across multiple countries, Thai requirements represent one component of a broader compliance framework that varies significantly by jurisdiction in both mandatory content and documentation standards.