How should I fill in the duration of stay and flight information for the DTV application form?

The form can be a bit misleading. For the duration of stay, just put 180 days, because that’s the official validity of the first entry under the DTV. Even if you plan to extend later to a year, the embassy/eVisa system wants to see 180 - anything longer can raise questions.

For the flight number section, it’s common not to have a ticket yet. You can usually leave it blank or just write ‘TBA’ (to be advised). Some people upload a refundable booking just to be safe, but it’s not always required.

Honestly, little details like this tripped me up a lot. That’s why I’d recommend getting a proper guide (search Thailand DTV Visa Guide by Niran Chaisiri on Amazon). It really cleared up these small but stressful parts and helped me avoid mistakes that could’ve delayed my approval.

It must link to your flight tickets

If the visa allows you to stay 180 days then you are not staying a year silly

Put your duration of stay at a little under 180 days. Give them the flight info for a flight you think you will take.

Note: I've been hearing the London consulate as been requesting proof of the flight in. So, if you happen to be applying there, be aware they might make that request.

Following for future reference

Put under 180 day stay, as you will have to leave the country before that.

Just google a flight number you think you are going to take and add that.