There are a lot of people in countries all over the world who can visit Thailand without needing to apply for a visa before they come in. If you are interested in this kind of entry, you will just need a valid passport and proof that you have transportation to take you out of the country. You can certainly extend your stay in Thailand, but only for up to 7 days. If you think you might be staying longer than that, you will have to get a tourist visa before going over.
The countries that are included in non-visa entry are: Australia, Austria, Bahrain, Belgium, Brazil, Brunei, Cameroon, Canada, Denmark, Finland, France, Germany, Greece, Hong Kong, Indonesia, India, Ireland, Israel, Italy, Japan, Kuwait, Luxembourg, Macau, Malaysia, Netherlands, New Zealand, Norway, Peru, Philippines, Portugal, Qatar, Singapore, South Africa, South Korea, Spain, Sweden, Switzerland, Turkey, United Kingdom of Great Britain and N. Ireland, United States of America, Vietnam.
You will also be able to apply for a tourist visa but you get to Thailand. Tourist visas are issued for stays up to 60 days, though you can extend yours an extra 30 days if you wish. You are not going to be guaranteed an extension, so you will need to keep that in mind.
If you want to stay for a longer period of time, you are going to have a number of options available. You can get a multiple-entry visitor visa. This visa will limit you to a certain number of times that you can enter the country. Each stay will be limited to 60 days, and when that period is up you’ll have to leave. There is no minimum length of time that you have to stay out of the country before you can come back.
Once your visa entries have expired, you will be able to use the non-visa entry scheme to extend your stay. Your “boarder runs” are going to be 30 days apart with this method. This means that you will only be able to stay in Thailand under this particular scheme for 90 days out of a 180 day period.
Another class of visas is available for those who want to spend a lot of time in Thailand. There are non-immigrant visas that are either single or multiple entry. Each stay will have a maximum of 90 days before a boarder run is required. These visas are valid for a total of 12 months. If you have multiple entry visa and your timing is correct, you will be able to stay for up to 90 days after the visa expires. The availability of these visas does vary with some consulates.
A lot of people tend to overstay their visas for many different reasons. Most people don’t encounter any problems, provided they leave the country voluntarily through the airport or border crossing. If you are caught in Thailand overstaying your visa, you will be deported at your own expense.
If you overstay your visa but leave of your own accord, you could have to pay a fine. There is no fine for overstaying your visa by one day, but overstaying by two days costs 1000 Baht, and every day after that is 500 Baht.
Make sure that you know exactly how long you are legally able to stay in the country, or else you could end up facing some very unpleasant consequences.