British citizens holding a full British passport are exempt from the visa requirement if the planned period of stay is up to 30 days.
This applies if you reach Thailand by air or by land. If you want to extend your stay once you arrive, you can do so once – the extension period is up to 30 days from the expiration date of your original visa.
Again, if you use the visa waiver option, remember that you can enter a total of three times within six months by air and two times per year by land crossing.
The total stay within six months (for air travelers) cannot be 90 days from the date of the first entry.
Therefore, if you travel frequently and need to travel in and out of Thailand several times, it is better to apply for a multiple entry visa before planning your trip.
In order to obtain a visa-free entry, you need to present the following documents at the point of entry:
Proof of sufficient financial resources to cover the length of stay in Thailand. This can be done with a traveler’s check or cash equivalent to 20,000 baht per person and 40,000 baht per family.
Proof of onward travel (this can be confirmed air tickets, train, bus or ship tickets), confirming that you intend to leave Thailand within 30 days of your arrival date. If you do not have a return ticket to show immigration, you will need to obtain a tourist visa before your trip. See our Tourist Visa section for details.
Note: you cannot overstay the 30-day period if you enter Thailand under a visa-free regime. Otherwise you will have to pay a fine of 500 baht per day, but not more than 20,000 baht. You may also be detained or deported and, even worse, blacklisted from re-entering Thailand.
Staying in Thailand for more than 30 days in one visit
If you plan to stay in Thailand for more than 30 days in one visit, you must obtain a tourist visa prior to arrival.
If you are entering the country for purposes other than tourism, you need to obtain a certain category of visa, such as a nonimmigrant visa.