The Thai government has been working since the early 2010s to facilitate and support electronic transactions. One of its biggest improvements has been made in the development of a platform for the preparation and delivery of electronic tax invoices and electronic receipts (e-Tax invoice and e-Receipt) for the Tax Revenue Department (TRD). With this platform, electronic transactions for the private and public sectors have been placed by international standards. The issue and submission of e-Tax invoices and e-Receipt have been completely optional since the date it was announced, and there is still no regulation on this issue.
e-Tax invoice and e-Receipt must be created in XML and PDF format. There are multiple ways to upload e-Tax invoices to the tax authority. For instance, large companies, which produce more than 500,000 invoices per month can send them directly to the tax authority, but companies that create fewer invoices must use a service provider. This intermediary must be approved by the government. Besides, on the website you can find the list of trusted service providers. Medium and small-sized companies can directly upload the XML file through the link shared by TRD.
It is mandatory to sign the issued XML file in all 3 ways, and this digital signature must be obtained by applying to one of the 2 e-Certificate service providers (Certification authority CA) determined by TRD. These digital signatures will not only be used to sign the XML file, but can also be used to log in to the platform with these electronic certificates.
Apart from the 3 upload ways mentioned above, small companies may upload e-Tax invoices & e-Receipts via email to the tax authority, and a timestamp is mandatory in this process. The issued e-Invoices have to be archived for at least 5 years.