Thailand runs e-invoicing as an opt-in system rather than a mandate. VAT-registered businesses that join the Revenue Department’s e-Tax Invoice & e-Receipt scheme issue digitally signed XML documents to the ETDA standard and submit them to the Revenue Department — no real-time clearance, but a hard requirement on signature validity and submission deadlines.
Thailand has no phases in the sense Saudi Arabia and the UAE have them. There is no date by which a Thai business must be issuing e-invoices, and no enforcement wave to be caught in. What there is instead is a voluntary scheme that opened to progressively smaller companies, a set of incentives used to pull businesses in, and a national plan with capability targets attached.
The legal groundwork came first: Revenue Department regulations recognised electronically signed tax invoices from 2012, and ETDA published the UBL-derived XML message standard that an e-Tax Invoice is still written in today.
The e-Tax Invoice & e-Receipt (RTIR) system opens alongside e-Tax Invoice by Email. They are separate schemes, not two settings of one: the email route takes a PDF through ETDA’s time-stamping service with no certificate and no XML, and is aimed at the smallest VAT registrants.
Cabinet approves a draft Ministerial Regulation to promote e-Tax systems — the signal that adoption would be driven deliberately rather than left to run.
Effective 1 January 2023, offering incentives through to 31 December 2025. That window has now closed. If a business case for e-invoicing in Thailand rests on enhanced tax deductions, confirm what has replaced it before you count the benefit.
The Revenue Department’s e-Tax portals confirm that authorised businesses may issue invoices and receipts in electronic or paper form, across B2B, B2C and B2G alike. Registering for the scheme does not take paper away from you.
Eligibility opened by annual sales, largest first. These are the dates the door opened, not dates anyone was pushed through it.
| Company size | Annual sales | Able to use e-invoicing since |
|---|---|---|
| Large | Over THB 500 million | 2018 |
| Medium | THB 30–500 million | 2018 |
| Small | THB 1.8–30 million | 2020 |
| Micro | Under THB 1.8 million | 2022 |
Full implementation is planned in stages. Read these as capability targets — what businesses should be able to do by each point — rather than as compliance deadlines with penalties behind them.
Large companies should be able to issue electronic invoices. This target date has now passed, so treat it as the baseline rather than something ahead of you — a large taxpayer not yet issuing electronically is behind the plan, not ahead of a deadline.
Large companies should be able to file their tax returns electronically. This is the stage that turns e-invoicing from a document-format question into a reporting-pipeline question, and where ERP data quality starts to matter more than the invoice template.
Every business should have the ability to file taxes electronically. At that point the voluntary scheme has effectively become the default way the Revenue Department expects to be dealt with, whether or not a mandate is ever legislated.
Thresholds, stage dates and incentive windows have all moved before and can move again. Verify everything here against the Revenue Department’s and ETDA’s current published guidance before go-live.
A certificate issued by a Thai licensed certification authority, held either by the company or by its service provider, is what makes an e-Tax Invoice legally valid.
Registration covers both bodies, with the route chosen to match the size of the business — the full e-Tax Invoice & e-Receipt system, or e-Tax Invoice by Email for smaller VAT registrants.
Documents are generated in the ETDA XML format, digitally signed and delivered to the buyer, then reported to the Revenue Department by the 15th of the following month — by upload, by service provider, or host-to-host.
Thailand is post-audit, not clearance. Nothing is cleared or stamped by the tax authority before the invoice reaches the buyer, so the invoice is valid at the moment it is signed — the opposite of ZATCA Phase 2, where an unstamped invoice is simply not an invoice. What replaces clearance is the digital signature and the monthly report, and those are where integrations fail: an expired certificate, an XML that does not validate against the ETDA schema, or a month’s documents that never reached the Revenue Department by the 15th.
The format follows ETDA’s recommendation for electronic tax invoice and receipt messages, derived from UBL, and carries the Thai-specific identifiers — the 13-digit Tax ID and the branch code that distinguishes a head office from each registered branch.
Thai and English on the same document, Buddhist Era dates alongside Gregorian, and a branch code that most ERP charts of accounts do not carry as a first-class field. Add the signing step itself: certificates expire, and a renewal that nobody tracked stops electronic issuance on the day it lapses. Then add the monthly cut-off — a reporting deadline on the 15th means month-end close and compliance stop being separate calendars. The work is less about the submission API than about getting clean, correctly identified data out of the ERP in the first place.
Because the scheme is voluntary, the risk is not a penalty for staying out. Paper remains permitted for authorised businesses across B2B, B2C and B2G, so nothing forces the change — which is exactly why Thailand is a business-case decision rather than a compliance project. The real exposure sits on the other side: once registered, documents must be properly signed and reported on time, and an expired certificate or a missed 15th is a failure you created by joining. Confirm your obligations and the current reporting calendar against the Revenue Department’s published guidance before go-live.