Do I need a departure flight if I have a Non-O visa and plan to extend my stay in Thailand?

The necessity of an onward flight when entering Thailand on a Non-O visa primarily lies with the airline's policies rather than Thailand's immigration regulations. Most airlines require proof of onward travel before allowing boarding, and if you travel without a visa, they might insist on showing your intent to leave the country within a specified period. While you can potentially buy a cheap, cancellable ticket to a nearby country as a solution, confirmation from your specific airline is essential. If granted a Non-O visa valid for 90 days, it’s typically advisable to have an onward ticket, but options like buy-before-you-fly services could alleviate this concern.