Can I extend my visa on arrival in Thailand for 6 months if I have a Philippine passport?

Jonai yes if you get a job your employer would then get all the documentation together and you would go to apply for a non-immigrant visa (probably in a neighbouring country like Laos) and then when you came back they would get you a work permit. With that visa you can keep extending as long as you have the job. When the job ends, you have to leave immediately. I believe there are a lot of Filipino English teachers working in Thailand- this would be one option for you.

The Ed visa is another option people who don't want to work use to remain longer-term. This is same deal, the school gets together the paperwork and then sends you out to get the non-immigrant visa somewhere like Laos, and then you extend it every 90 days as long as you are studying.

If you only want six months though you should be able to manage that without too much difficulty on a combination of tourist visas, extensions and visa exempt entries. These other options are really for people who want to stay longer.

@Jo***

you can't no, unless you get a job or enroll in a course for education, or are over 50, or marry a Thai person, and in most of these cases you would need to leave anyway to get the non-immigrant visa. There are education options in Chiang Mai (learning Thai, self-defence) that can qualify you for a non-immigrant for up to a year at a time (renew every 90 days in Chiang Mai without leaving).

@Jo***

yes if you have spent a lot of time previously in Thailand, but with regard to Vientiane they are usually looking for prior visas from Laos specifically, my understanding is they would not count the visa you got in Vietnam as part of your "history", it's history with consulates in Laos they are concerned with. If you get a certain number of visas in Laos at some point they will stamp your passport with a "no more tourist visas" stamp, which means you can't get any more there. But it's at least 3 or 4 I think before they stamp you.

Jonai that is correct. That gets you 60 days.

Then you can fly to Udon Thani (on Nok- cheap internal flight) and go to Vientiane, Laos to get a SETV. That gives you 60 days which you can extend again by 30. So you are up to 5 months then.

Then you can do a border run by getting a bus to Mae Sai and going over to Myanmar and back. This gets you 30 days, which you can extend by a further 30- so you are at 7 months then. Note you can only do 2 visa-exempt land entries per calendar year but I checked and the Philippines is on the list of countries this was extended to 30 days by land at the start of this year.

Or some combination of the above. Note that Thai immigration may be more picky with people from the Philippines but I believe if nothing has changed recently Vientiane will give you a SETV and you can do a land border run and you should be able to swing 6 months this way if you do not have history.

The only way you can get a 6 months tourist visa (METV) is by going to the embassy in Manila- you need to get that in your home country.