Bangkok Bank London

I came across this information today on the website of Credit Suisse, a bank in Switzerland:

Quote

 

All payments to Thailand must include
a code to indicate the payment
purpose.

 

The code must reflect the actual reason for payment. The
payment purpose must also be listed in English. If the code is
missing or incorrectly selected (entered code does not match the
reason for payment), additional delays and/or rejections may
occur. In all cases, additional costs may be incurred.

 

For payment orders in the equivalent of THB 5 million (Thai baht)
or above, additional documents may be required. These are
generally documents explaining the background of the transaction,
such as an invoice that the payee sent to the payer. There
may be inquiries from the beneficiary bank. In these cases,
Credit Suisse will notify you.

 

Source, with list of codes: https://www.credit-suisse.com/media/assets/private-banking/docs/ch/unternehmen/unternehmen-unternehmer/zahlungen-thailand-en.pdf

Another Swiss bank, Banca Migros, has this list of purpose codes of Siam Commercial Bank) SCB on its website

https://www.migrosbank.ch/dam/jcr:f877254a-e85e-47ac-8a44-1710700f03a7/downloads/de/infoblatt/zahlen/verwendungscodes-thailand.pdf