On a monthly programming retainer, does the client withhold 3% every month?

Yes. If the client is a juristic person, they withhold 3% on each monthly fee and issue a 50 Tawi each time, which you total up as a credit for the year.

What withholding tax rate applies to a Programmer?

Generally 3% when the client is a juristic person. For example, a ฿45,000.00 fee is withheld ฿1,350.00, so you receive ฿43,650.00.

Does a Programmer issue the 50 Tawi themselves?

No. On your sales invoice the client withholds and issues the 50 Tawi to you; your job is to keep it as evidence to credit on your annual return.

Freelancer guide

Invoicing & tax for a Programmer in Thailand

Software development and contract programming for a company is a service / hire-of-work fee, withheld at 3% when the client is a juristic person.

By the BillsOS team · Updated 8 Jun 2026

A worked example

Say you are a Programmer invoicing a corporate client ฿45,000.00 for your work. The income type is “Service / hire-of-work fees”, withheld at 3%. The figures below come straight from the BillsOS engine.

Fee (before VAT)	฿45,000.00
Total invoiced	฿45,000.00
Less withholding tax 3%	-฿1,350.00
Net the client pays (QR amount)	฿43,650.00

The client withholds ฿1,350.00 and transfers you ฿43,650.00, handing you a 50 Tawi certificate as evidence.

Who withholds: On your own sales invoice you are the payee. Your client (the payer) is the one who withholds the tax and issues you the 50 Tawi — you do not issue it yourself.

What to watch for in this trade

For long builds paid in milestones, the client withholds 3% on each instalment — keep the 50 Tawi for every milestone so you can credit it all back at year-end.

Documents you’ll need

Receipt — if not VAT-registered you issue a receipt (only VAT-registered persons issue tax invoices)
Quotation and invoice — before the work and when you bill
50 Tawi — received from the client and kept for every job, to credit on your annual return

Tools & guides for this

BillsOS issues invoices and receipts that compute the withholding for you, with an exact-amount PromptPay QR embedded so the client scans and pays straight into your own account.

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BillsOS only formats and computes documents for you. This is general information, not tax advice — please confirm with the Revenue Department or your accountant.