A full tax invoice in Thailand must carry the words “tax invoice”, the name, address and tax ID of seller and buyer, a running number, a description of the goods or services and the VAT shown separately from the price. Only VAT-registered businesses may issue one, and the buyer needs it to claim input tax.
The Revenue Code lists what a full tax invoice must show. At the top, the words “tax invoice” in Thai, then the name, address and tax identification number of the seller, together with the branch number where the seller operates through branches. The buyer’s name, address and tax ID follow, and for a business customer the branch information must match the branch that bought the goods.
The body shows a running document number, the date of issue, the kind, quantity and value of the goods or services, and the VAT amount stated separately from the price. If the price is quoted inclusive of VAT, the invoice still has to break out the tax. The document is expected to be written in Thai, and other languages may be shown alongside; ask your accountant how to present foreign-currency amounts.
A missing item is not a cosmetic flaw. The buyer cannot rely on an incomplete document to claim input tax, and the seller can be fined for issuing one. The commonest gaps are the buyer’s tax ID, the branch code and an address that differs from the one registered.
A VAT-registered seller dealing with the public, such as a shop or restaurant, may issue an abbreviated tax invoice, which carries fewer details and no buyer information. A business customer who wants to claim input tax needs a full invoice in the company’s name, so a till slip alone will not do. Offer the full version when a company buys.
A tax invoice is not the same as a receipt or a plain invoice. A seller who is not VAT-registered cannot issue a tax invoice at all, and a VAT-registered seller sometimes issues a separate delivery note or receipt. Some businesses combine tax invoice and receipt in one document, which the Code permits when all required particulars are present.
Keep a consistent practice for each type of customer and train the sales and finance teams to use the right document. Confusion between a quotation, an invoice and a tax invoice is one of the most frequent causes of rework at month-end.
The tax invoice is issued when the tax liability arises, which for goods is normally at delivery or payment and for services at payment, whichever the law makes the tax point. An advance payment can therefore require a tax invoice before the work is done, and the final invoice later credits the advance.
Mistakes are corrected with a credit note or debit note, not by overwriting. A credit note reduces the value of a previous supply, for example after a return or a price cut, and a debit note increases it. Both refer to the original tax invoice and must be recorded in the month they are issued. Handing back and reissuing the original is risky because the document number sequence breaks.
If a customer asks for a tax invoice weeks after the sale, check the rules before issuing it back-dated. Issuing a document late has consequences for the period in which the output tax is declared.
The Revenue Department operates an e-Tax Invoice and e-Receipt system under which a registered business issues tax documents electronically, with a digital signature or an approved intermediary, and sends the data to the Department. Enrolment is voluntary, is done with the Department itself and carries technical requirements about certificates and time stamps.
The attraction is less paper, faster delivery to customers and, in some programmes, simpler record-keeping. The cost is a project to adapt the invoicing process and to maintain the signing certificates. Businesses with high invoice volumes tend to find the investment worthwhile, while small businesses often stay with PDF invoices.
Whichever route you take, the underlying content of the invoice is the same, and the retention duty is unchanged: documents must be kept and producible during a Revenue inspection.
Number invoices in an unbroken sequence per series, never reuse a number and keep a register of voided numbers with the reason. Store the issued PDF together with the matching delivery or order record so an inspector can follow the transaction from start to finish.
4invoices can produce PDF invoices from the details you enter and keep them in an archive. You are responsible for entering the correct tax IDs, branches and VAT amounts, and for deciding that a document qualifies as a full tax invoice. The product does not certify documents, does not connect to the e-Tax Invoice system and does not send anything to the Revenue Department.
The first recurring error is an invoice issued to the wrong legal name, for instance the trading name or the director’s name instead of the registered company name. The buyer’s input tax claim then fails, and the seller is asked for a corrected document months later. Take the name and tax ID from the buyer’s DBD certificate, not from a business card.
The second is a branch problem. Thai companies may register head office and branches separately, and a tax invoice must identify the right one. A head office that buys for a branch and receives an invoice in the head office name can create a mismatch in the buyer’s records, so ask the customer which entity is purchasing before the invoice is raised.
The third is VAT shown as a lump sum without a clear base. If an invoice states only a total, an inspector cannot confirm that the tax is correct. Always show the price before VAT, the VAT amount and the total, and make sure the three figures reconcile to the baht.
The fourth is delay. Tax invoices that are produced days after the tax point, or batched at month-end, push output tax into the wrong period and complicate the PP.30 reconciliation.
Invoice templates miss legally required particulars, such as the buyer tax ID or branch.
Check your invoice template against the particulars in the Revenue Code and enter the buyer’s tax ID or branch yourself. 4invoices issues PDF invoices; it does not certify them as full tax invoices.
Document numbers skip or repeat when several people invoice at once.
Set your own continuous document numbering and keep issued invoices in the archive; confirm the requirements with your accountant. The system does not connect to the Revenue Department e-Tax Invoice system.
A customer returns part of an order and the finance team edits the original invoice to reflect it.
Issue a credit note that refers to the original by number and date, and keep both documents in the archive. The credit note details are entered by you, and the system does not adjust the VAT return.
The document must be headed “tax invoice” in Thai and show the seller’s and buyer’s names, addresses and tax IDs, the branch where relevant, a running number, the date, a description of the goods or services and the VAT stated separately. Ask your accountant for the current checklist, since the Revenue Department updates its forms and guidance.
No. Only a VAT-registered business may issue a tax invoice, and a business that is not registered but charges VAT commits an offence. If you are below the threshold and unregistered, issue an ordinary invoice or receipt without VAT, and register once you cross THB 1.8 million of annual sales.
Do not overwrite it. Issue a credit note to cancel or reduce the original and, where needed, a new correct tax invoice, referring to the first document by number and date. Both are recorded in the month they are issued, and the customer should receive copies so that their input tax claim matches.
Enrolment in the Revenue Department e-Tax Invoice and e-Receipt system is voluntary for most businesses, although the Department encourages it and some contracts may require it. Ordinary paper or PDF tax invoices that contain the required particulars remain valid. Check the current rules with the Department before making a decision.
Keep issued and received tax invoices with the ledgers for at least five years, and longer where the Revenue Department or your auditor requires it. Store them where an inspector can find the document behind each figure in a monthly return, and keep an index so retrieval does not depend on one employee’s memory.
Full tax invoices and e-Tax Invoice must follow the Revenue Department rules.
