Thailand licenses its exchange booths. A non-bank money changer holds a permit from the Ministry of Finance, administered through the Bank of Thailand, and the permit’s published rules set what the booth must put on the wall, what it must hand you, and how much foreign currency it may sell you in a day. They do not guarantee a good rate. They give you a short list of things to check before you hand over your notes.
Only licensed operators may exchange your money
The Bank of Thailand administers foreign exchange for the Ministry of Finance, and the requirement is clear: “all foreign exchange transactions including purchase, sale, exchange or transfer of foreign currencies are required to be conducted with the persons who are granted foreign exchange licenses by the Minister of Finance.”
There are nine licence categories. Two matter to a traveller: authorized juristic persons, which are the commercial banks, and authorized money changers, which the Bank of Thailand defines as “Non-bank companies authorized to conduct the business relating to buying and selling foreign currency banknotes.” The second is the standalone booth in a mall, hotel lobby or airport terminal, with a numbered permit of its own.
What must be on display
The operating rules sit in the Bank of Thailand’s Notice of the Competent Officer on Rules and Practices regarding the Undertaking of Authorized Money Changers. Clause 7 requires a money changer to operate “only at the authorized offices” and to display, in conspicuous places:
- its Ministry of Finance permit
- its “Daily buying and selling rates of foreign currency notes or traveler’s cheques payable in foreign currency for all currencies which the authorized money changers purchase or sell”
- a statement reading “Authorized Money Changer License No……….”.
You can check two of these at a glance. The rate board has to cover every currency the booth deals in, so a board listing only the few with the widest margins falls short. The licence number has to appear as a written statement, which a logo does not satisfy. A booth showing neither is outside the rules the rest of this page relies on.
Rates follow a published average, with no cap
Clause 8 requires that “The buying or selling rates used by the authorized money changers for purchasing or selling of foreign banknote or purchasing traveler’s cheques shall be quoted in line with average buying or selling rates of authorized juristic persons published by the Bank of Thailand”.
The benchmark is the average of the commercial banks’ own rates, which the Bank of Thailand publishes daily as its series on the rates of exchange of commercial banks in Bangkok. It is not the mid-market rate a currency app shows. A money changer’s board is supposed to sit in line with that average.
The rule stops there. “In line with” is not defined, no numeric tolerance is given, and the notice sets no maximum spread. It requires a booth to track a benchmark and does not control its price, so one licensed booth can be meaningfully worse than the next along the concourse. Compare two boards.
It also explains why a rate in a currency app will not match the board. The app quotes the mid-market rate. The board is anchored to an average of commercial bank rates, which already sits on the other side of a spread, and only the board’s rate is one anyone can hand you at a counter. If the mid-market rate is the number you want, the conversion has to happen somewhere other than a booth.
Denominations are separate lines
Large notes are quoted differently from small ones because a Thai bank’s published sheet gives each denomination band its own row and rate. Siam Commercial Bank’s published foreign exchange rates carry three US dollar lines, labelled “USD = US Dollar $50-$100”, “USD1 = US Dollar $5-$20” and “USD2 = US Dollar $1-$2”. On that sheet a hundred dollar bill and a ten dollar bill are different products.
The Bank of Thailand’s notice does not set those bands. It does require the transaction record to state the “Type of bank notes, amount and currency of notes purchased or sold”, so the denomination you handed over is part of the documented deal.
The bank says two more things about its own sheet. On timing: “There is no fixed number of times that foreign exchange rates are updated each day.” On location: “Exchange rates may vary across different SCB service locations.” It advises checking the displayed date and time alongside the rate before every transaction. The same page separates cash from transfers. The rate for banknotes over a counter is the notes rate, not the telegraphic transfer rate that currency apps tend to resemble.
Buying foreign currency is capped and needs a passport
The rules are asymmetric, and most travellers meet the other half on the way home. A money changer “may purchase foreign currency notes or traveler’s cheques payable in foreign currencies from customers without any limit”, though from 50,000 baht equivalent upward it must take a copy of an identity document.
Selling you foreign currency is bounded twice. A money changer may sell foreign currency notes to a customer only “for travel purpose”, and only up to a daily ceiling that depends on its permit class:
- 800,000 baht equivalent per day per customer for the main licence categories
- 200,000 baht per day per customer for the border and tourism sole proprietorships
Below 50,000 baht equivalent the booth needs a photocopy of your passport or a certificate showing you are travelling abroad. From 50,000 baht upward it needs that plus a photocopy of your identification card.
Turning dollars into baht is unlimited. Turning baht back into dollars is a documented transaction with a ceiling, so plan for it if you will leave Thailand holding a meaningful amount of baht. The ceiling and the travel-document requirement apply only to notes bought across a counter. Holding the baht in an account that converts it for you, Wise among them, takes the transaction off the counter and outside these rules.
Checks before you hand over the notes
Every check comes from the rules themselves, not from a preference for one chain of booths.
- Look for the posted licence number and the full rate board. Both are required, so their absence is a real signal.
- Confirm which denomination band your notes fall into. It is a separate priced line, not a rounding difference.
- Note the date and time displayed on the board.
- Ask for the transaction record, which the notice requires the changer to give you and keep a copy of. Read the rate and note type on it against the board you were quoted from. If they disagree, you hold the document that says so.
This page cannot tell you what happens when a booth breaks these rules. The notice sets out what a money changer must do and the grounds on which the Minister may revoke or decline to renew a permit, including acts that would endanger the exchange system. It describes no complaint route for a customer and no penalty for a mis-stated rate. If a transaction goes wrong, the record you are entitled to is your evidence, and the Bank of Thailand is the body that licenses the counter.
Converting leftover baht without the counter's daily cap (affiliate link)