Thailand draws a sharp line between two documents that English-speaking businesses often treat as one. An invoice is a commercial request for payment. A tax invoice (ใบกำกับภาษี, bai gamgab pasi) is a formal document defined by the Thai Revenue Code, and only a VAT-registered business may issue one.
That distinction matters commercially, not just legally. Your Thai client cannot claim input VAT without a valid tax invoice. If you send a plain invoice when they expected a tax invoice, their accounts team will ask for a replacement — and payment usually waits until it arrives.
This guide covers what belongs on a Thai tax invoice, when you need to register for VAT, how withholding tax changes what you actually get paid, and what foreign businesses invoicing into Thailand should know.
This is general information, not tax or legal advice. Thai tax rules are administered by the Revenue Department and change periodically. Verify anything affecting your business with the Thai Revenue Department or a licensed Thai accountant.
Invoice vs tax invoice: which one do you issue?
If you are not VAT-registered in Thailand, you issue an ordinary invoice or a bill. You must not label it a tax invoice and must not add VAT.
If you are VAT-registered, you must issue a tax invoice for each taxable supply, at the point the tax liability arises — generally on delivery of goods or on payment for services.
Issuing a document headed "Tax Invoice" without VAT registration is a serious matter in Thailand, not a formatting slip. When in doubt, call it an invoice.
What a Thai tax invoice must contain
Section 86/4 of the Revenue Code sets out the required particulars:
1. The words "Tax Invoice"
The document must be visibly marked as one — ใบกำกับภาษี. Bilingual headings showing both the Thai and "Tax Invoice" are standard practice and reduce friction with accounting teams.
2. Your name, address, and Tax ID
The seller's registered name and address, plus the 13-digit Taxpayer Identification Number. For companies this is the same as the corporate registration number.
3. The buyer's name, address, and Tax ID
Same detail for the purchaser. For business customers, their 13-digit Tax ID is expected, and its absence is a frequent reason invoices come back.
4. Head office or branch identifier
Thailand treats branches as distinct establishments for VAT. Invoices commonly show the branch code — 00000 for a head office (สำนักงานใหญ่), or the five-digit branch number. Getting this wrong on a business-to-business invoice is one of the more common corrections requested.
5. A sequential tax invoice number
Numbers must run in sequence. Many businesses include a book or volume reference alongside the running number.
6. Description, quantity, and value
The nature and quantity of goods or services, with the value of each line.
7. VAT amount, shown separately
The VAT must appear as its own line, clearly separated from the value of the goods or services. A single VAT-inclusive total is not sufficient.
8. Date of issue
The date the tax invoice was issued.
VAT in Thailand
The standard VAT rate is 7%. This is technically a reduced rate that has been extended repeatedly by royal decree from a statutory 10% — it has been held at 7% for many years, but because it is renewed rather than permanent, it is worth confirming the current rate each year.
Registration is mandatory once annual turnover from taxable supplies exceeds 1.8 million baht. Below that, registration is voluntary. Voluntary registration can be worth it if your customers are themselves VAT-registered businesses who want to reclaim input tax, and unhelpful if you sell mainly to consumers.
Certain supplies are zero-rated — notably exported goods and some services performed in Thailand but used abroad. Zero-rated is not the same as exempt: with zero-rating you still issue a tax invoice, still file returns, and can still recover input VAT.
Withholding tax: why you get paid less than you invoiced
This surprises almost every business new to Thailand. For many service payments, a Thai company paying you is legally required to withhold a percentage of the fee and remit it to the Revenue Department on your behalf.
Common rates for domestic payments include 3% for most services and professional fees, and 5% for rental payments. Advertising services commonly attract 2%.
Two practical consequences:
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Your bank receipt will not match your invoice total. On a ฿100,000 service invoice with 7% VAT and 3% withholding, the client pays ฿107,000 in VAT-inclusive terms but withholds ฿3,000 — calculated on the pre-VAT amount — so you receive ฿104,000.
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You must collect the withholding certificate. The payer issues a หนังสือรับรองการหักภาษี ณ ที่จ่าย (withholding tax certificate). That document is what lets you credit the withheld amount against your own tax liability. Without it, the money is simply gone from your perspective. Chase it at the time of payment, not at year end.
Many Thai invoices include a line noting the expected withholding so both sides reconcile to the same figure.
Language and currency
Thai tax invoices should be in Thai. The Revenue Department may permit English, and bilingual Thai/English invoices are extremely common in practice — particularly with international clients — but Thai is the default expectation, and a purely English document can be questioned.
Amounts should be in baht. If you invoice in a foreign currency, the baht equivalent and the exchange rate used need to be shown so the VAT figure is verifiable.
If you are a foreign business invoicing a Thai client
If you have no permanent establishment in Thailand, you generally do not register for Thai VAT and do not issue Thai tax invoices. Instead:
- You send an ordinary commercial invoice.
- Your Thai client may need to self-assess VAT on the imported service and remit it using form P.P.36.
- Your client may also be required to withhold tax on the payment, at a rate that depends on the nature of the service and on whether a double tax agreement exists between Thailand and your country.
Thailand has an extensive treaty network, and treaty rates are often lower than the domestic default — but claiming the reduced rate usually requires you to supply a certificate of residence from your own tax authority. Agree this with your client before invoicing, not after they have already withheld at the higher rate.
Practical checklist
- Are you VAT-registered in Thailand? If not, do not issue a "Tax Invoice"
- Document clearly headed as a tax invoice, ideally bilingual
- Your name, address, and 13-digit Tax ID
- Buyer's name, address, and Tax ID
- Head office or branch code
- Sequential number
- Line-by-line description, quantity, and value
- VAT shown as a separate line, not folded into the total
- Date of issue
- Withholding tax noted, if the client will deduct it
- Baht amounts, with the exchange rate if invoicing in another currency
FAQ
Can I issue a tax invoice if I am not VAT-registered?
No. Only VAT-registered businesses may issue tax invoices in Thailand. Issue a normal invoice or bill instead, with no VAT line and no "Tax Invoice" heading.
Do I have to register for VAT in Thailand?
Registration becomes mandatory once your annual taxable turnover exceeds 1.8 million baht. Below that it is optional. Voluntary registration mainly helps when your customers are VAT-registered businesses who want to reclaim the input tax.
Why did my client pay less than the invoice amount?
Almost certainly withholding tax. Thai payers must withhold a percentage of many service payments — commonly 3% — and remit it to the Revenue Department. Ask for the withholding tax certificate, which lets you offset the withheld amount against your own liability.
Does my invoice have to be in Thai?
Thai is the expected language for tax invoices. Bilingual Thai/English invoices are widely used and generally accepted, and are the safest option if you serve both local and international clients.
What is the difference between zero-rated and exempt?
With zero-rated supplies you charge VAT at 0%, still issue tax invoices, still file returns, and can recover input VAT on your costs. With exempt supplies you fall outside the VAT system for those sales and cannot recover related input VAT. Exports are typically zero-rated rather than exempt.
What is the branch code on Thai invoices?
Thailand treats each registered establishment separately for VAT. Invoices show which establishment made the supply: 00000 for a head office, or the specific five-digit branch number. Business clients frequently reject invoices carrying the wrong code.