For companies engaged in service business, one must remember how to prepare the invoice, tax invoice and receipt properly.

  1. The invoice, receipt/tax invoice should have a letterhead showing the full official name of the company, its registered address, tax ID number (not to be confused with VAT number) and the word “Headquarters” in case it is issued by the headquarters. For some companies with branch offices, they will put “Branch no. XX” if that certain branch office issues the documents.
  2. Followed the letterhead, it should be the name of the document (i.e. “INVOICE” or “RECEIPT” or “TAX INVOICE” or “RECEIPT/TAX INVOICE”.
  3. The invoice, tax invoice and receipt should have 3 separate sets of running sequence. Sometimes, you invoice your clients and they never pay you, or they pay 3 invoices in one payment, so you issue only one receipt and tax invoice. Sometimes, you also issue an invoice for reimbursement of expenses that may not have VAT in there so when you get paid, you will issue only a receipt but not a tax invoice. The sequence of each kind of documents cannot skip a number. You cannot have 1,2,3,5 and 4 is missing. In the event that you have to cancel an invoice, it is highly recommended to consult with your accountant like us. We suggest you use the following sets of running numbers:
  • a) Invoice No.: I250501 where it means Invoice, 25 is the year 2025, 05 is the month of May and 01 is the sequence of the invoice (this indicates how many invoices you have issued so far during May 2025).
  • b) Tax Invoice No.: T250501 where T means Tax Invoice, 25 is the year 2025, 05 is the month of May and 01 is the sequence of the invoice.
  • c) Receipt No.: R250501 where R means Receipt, 25 is the year 2025, 05 is the month of May and 01 is the sequence of the invoice.
  1. Each kind of document should have 1 original and 2 or 3 copies. The original goes to the client, one copy goes to your accountant and you keep 1-2 copies. Some of your clients, specially if they are bigger companies, they prefer to have one original and at least one copy. Thus, the first page of the invoice or tax invoice/receipt should bear the word “INVOICE” (or TAX INVOICE or RECEIPT). The 2nd, 3rd and 4th should bear the name of the document and the word COPY (e.g. INVOICE (COPY).

Normally, when you invoice your clients for your services or deposits, you give them an invoice only. This is because you are a service business so you do not need to issue a Tax Invoice until you get paid. So, some companies combine their receipt and tax invoice into one document which they issue when they get paid (RECEIPT/TAX INVOICE).

Contact MSNA for further assistance in accounting, tax filing and expert advice on Thai taxation.