You need to prepare the documents regarding the application for the Visa in Thailand in person, or your employing organization can do it on your behalf.
Once the documents are ready, you may choose to submit them through mail or in-person at the Thai embassy or Consulate while being in your home country.
You need to check for the consulate fee and payments required by the embassy and the payment method they accept.
It takes about 5-10 days on average for an embassy or a consulate to process your documents. However, it is highly subjective to the workload present in the office. Remember to attach a supporting document along with your documentation to avoid further delays.
Currently, you can change from a Tourist Visa to Non-Immigrant B Visa without having to first leave Thailand. However, these requirements change over time, so it’s best to check beforehand the best options for making the application while being in your home country to ensure your Non-B visa is secured.
There are only 2 categories under which they can be considered applicable for this type of visa for foreigners.
If you are a foreigner and wish to carry out business in Thailand, you should apply for a Thai Non-Immigrant B visa.
For all people who plan to leave Thailand and then re-enter, they will have to apply for a Re-entry permit from the Immigration office or the international airport before leaving Thailand. Only then will you be allowed to re-enter Thailand.