Also asked, is it mandatory to book return ticket for visitor visa?
Return ticket is not only compulsory but also return ticket needs to be confirmed. For my wife, i booked tourist visa (90 days) & booked tickets through emirates airlines, they gave OK TO BOARD after showing them the valid visa & the confirmed return ticket. So, make sure you check with the airlines before proceeding.
Beside above, can you enter Korea with a one way ticket? You will need some form of onward ticket. Korean immigration doesn't even enter into it: Without the ticket the airline will not even let you board the flight to Korea. Personal experience: When we went to Korea on a one-way ticket (via HK on Thai) they would not let us check in online.
Similarly, it is asked, do I need a return ticket?
Some airlines are very strict about the proof of onward travel rule. If you can't provide proof, you won't be allowed to board your flight. Or they'll ask you to buy a return ticket from them right then and there — which can often cost hundreds of dollars more than you want to spend.
Do I need a return ticket to enter Taiwan?
For U.S. citizens, all U.S. passport holders will be allowed to enter Taiwan without a visa for up to 90 days if their passport is valid throughout their intended length of stay and the traveler has a confirmed return air ticket or proof of onward travel.
