Thailand Visa and Passport Requirements

To enter Thailand, a passport valid for six months is required by all nationals referred to in the chart above.

Travellers coming from or have recently travelled through yellow fever-infected areas may be required to show a yellow fever vaccination certificate before being allowed to enter Thailand.

Visas for Thailand are not required by all nationals referred to in the chart above for touristic stays of up to 30 days if entering via an international airport. If entering by land, you will usually be granted a stay of 15 days (apart from nationals of Canada, France, Germany, Italy, the UK and the USA, who will be granted a 30-day stay). All visitors must hold valid passports, sufficient funds and confirmed airline tickets to leave Thailand within the time allowed by their entry stamp. Exceptions to the visa requirements are:

Nationals of Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, Sweden and the UK are also eligible to apply for an ACMECS visa, which is a 90-day joint visa allowing entry to Thailand and Cambodia. It's only really worth obtaining this visa if you're planning on spending more than 30 days in Thailand however.
Nationals not referred to in the chart are advised to contact the embassy to check visa requirements.

Visa on arrival: ฿1,000; transit visa: £20; tourist visa: £25 (per entry).
If you apply for an ACMECS visa from the Thai Embassy, you pay the usual tourist visa fee for Thailand then pay Cambodia's tourist visa fee at the international border.

Visa on arrival: 15 days; transit visa: 30 days; tourist visa: 30 or 60 days.
Transit visas and single-entry tourist visas are valid for three months from the date of issue. Two- or three-entry visas are valid for six months from the date of issue.
The ACMECS visa is valid for 90 days from the date of issue, allowing up to 60 days in Thailand and up to 30 days in Cambodia.

Nearest consulate (or consular section at embassy).

Visitors to Thailand who wish to conduct business, work or study in the country can apply for a non-immigrant visa. This allows holders a stay for up to 90 days. In addition, to be able to work, visitors must hold a work permit issued by the Ministry of Labour.

Applications to the embassy must be made in person. You can usually pick up your visa the day after you drop off your application.

Proof of adequate finances for the duration of your stay in Thailand is required at the point of entry into the country (ie traveller’s cheques and/or cash equivalent to ฿10,000 per person and ฿20,000 per family). In practice, you are unlikely to need to show this, but be prepared nonetheless.

Visa-exempt nationals wishing to leave Thailand and re-enter the country after their initial 15 or 30 days may only stay for a maximum of 90 days in a six-month period.
Be wary of visa-run or visa extension services offering to renew your visa - these are illegal and each year a number of tourists are jailed, having turned up to border crossings with a fake Thailand visa or entry stamp in their passport.
Thailand visa extensions must be made before the current visa runs out. A lengthy overstay can incur a maximum penalty of a spell in jail before being deported and banned from returning to the country. If you wish to extend your stay, contact the Immigration Bureau (www.immigration.go.th).

Children travelling with one parent or alone must have a notarised letter of consent from one or both parents.

An incoming passenger can import up to two pets at one time.
These include all domestic animals such as dogs, birds, cats etc subject to the production of a required health certificate from their country of origin. Pets are still liable for the usual quarantine checks upon arrival.

Royal Thai Embassy in the USA 
Telephone: (202) 944 3600 Website: http://www.thaiembdc.org Opening times: Mon-Fri: 0900-1230 and 1400-1700, 0900-1200 and 1400-1700 (consular section). 
Royal Thai Embassy in the UK 
Telephone: (020) 7589 2944 Website: http://www.thaiembassyuk.org.uk Opening times: Mon-Fri 0930-1230; Consular section: Mon-Fri 0930-1230, 1400-1700. 
British Embassy in Thailand 
Telephone: 02 305 8333 Website: http://ukinthailand.fco.gov.uk/en/ Opening times: Office hours Mon-Thurs 0800-1200 / 1245-1630; Fri 0800-1300.