BritTim

At one time (well over a decade ago) the change in visa status could only be done in Bangkok. For a time, it was Bangkok or some other major immigration offices. For a long time, it has been possible to do it at any immigration office. The application is taken under consideration and sent to division headquarters for endorsement.

Some immigration offices insist on bank statements, even when using the money in the bank option. The purported reason is that the bank book might not provide a complete history of transactions on your account (consolidated entries) and a transitory drop below the required minimum might have occurred. Even when there are no consolidated entries in your bank book, some immigration offices force you to get the statements as a matter of principle.

The normal meaning of "back-to-back" is consecutive entries with no (or minimal) gap between them.

If you can find the right school, that should be possible. Are you intending an intensive course (several hours each day)? There are some high quality, but expensive, courses of that nature, typically targeted at business people.

Since visa exemptions are under bilateral agreement, the two by land per calendar year limitation does not apply. I think there were some restrictions prior to the Russo-Ukrainian war, but Thai immigration is being lenient with Russians right now.

Note that an alternative to getting a Non O visa at Immigration (after entering visa exempt) is to get a Non O visa at a consulate like Savannakhet. The advantage is that you have the visa the next day rather than there being an under consideration period.

If you can get an appointment in Vientiane, and they do not ask to see your old passport, you have a good chance of getting a tourist visa in Vientiane. With a visa, you can safely return via the Friendship Bridge to Nong Khai. Your chances of a visa exempt entry by air would be poor because immigration can see your whole history. You might have a better chance of a tourist visa, if Vientiane wants to look at your old passport, in Yangon or Kota Bharu (not very convenient to travel to). Your days as a long stay tourist are likely close to over. Plan accordingly.

It is understandable that they would because (with some exceptions that do not apply to most) Cambodian law mandates an overnight stay.

The obvious place to go is still Penang. The problem is the extreme crowds often encountered there. If you do not mind queuing well before the consulate opens, that would be my suggestion. If the application does not need to be immediate, another decent option would be to make an appointment and apply in Vientiane.

In spite of the position of the immigration office and check point, it is true that the casinos are regarded as part of Cambodia. Officially, you must check out of Thailand to visit them, and will not be allowed back into Thailand if you do not have stamps indicating that you entered Cambodia.

Manila is known to be tough on tourist visa applicants. I am actually mildly surprised you were successful.

The "travels frequently to Thailand as a tourist" annotation has been used at a number of embassies and consulates over the years. It greatly reduces your chance of further tourist visas until the next time you replace your passport. The other message is not something I have seen before. It is obviously an indication to other consular and immigration officials that you told them your plans, and your credibility will not be high if you do something else.

My sense is that they want to see general evidence that you are not broke. Nothing in the account until two days previously, and then exactly 20,000 baht to meet a threshold would be looked at with scepticism. If you have a fluctuating balance over the three months with the amount generally above 20,000 baht, I think that would be accepted. They are not going to deny you because the balance occasionally drops below 20,000 (unless they really want to deny you for other reasons).

It is tough finding announcements of rules changes from 15 years ago. If I have some free time, I might track it down. (I may need to use archive.org.) I can distinctly remember when the rule change was announced. At the time, I was using visa exempt entries. Old rules frequently hang around on some or all websites. Often, erroneous information is even copied forward onto new sites. The current rules on visa exemptions (excluding those based on bilateral agreement) are: by land you are restricted to two per calendar year; and by air, there are no explicit limits, but the officials are supposed to use their judgement on whether visa exemptions are being used in an appropriate manner (in particular, using them to extend a consecutive stay in Thailand for longer than is consistent with regular tourism). Obviously, the guidelines to airport officials are pretty vague, and different officials will interpret them in various ways.

Biggest procedural difference: at Savannakhet you receive the visa the next day; if applying at Immigration, it is taken under consideration and takes about a month.

The rule was in force for less than six months in, as far as I remember, 2008. It proved totally impracticable to enforce (especially at land crossings where visa exempt entries were for only 15 days, and it could take several minutes for the official to scan your passport and add up the number of days you had been in Thailand on visa exemptions). I am aware that this rule is still often cited in web pages, but it went away about 15 years ago. This 11-year-old thread talks about these oft cited 90 days in six months and 180-day per year rules closer to the time when they had been abolished: https://aseannow.com/topic/534748-180-day-rule-and-90-days-within-180-days-rule-explained/

Immigration officials might take that into account, but there was only a clearcut 90 days in six-month period on visa exemptions rule for a very short period many years ago. No such rule exists today.

You can be married abroad to a Thai and still not eligible for a Non O visa. The most obvious example is same sex marriage, but polygamous marriages (legal, for example for Muslims, in some countries) would also not qualify.

Nothing except the need to travel back to his home country, and stay there for a couple of weeks while making the application. This would need to be repeated every couple of years. It is understandable if he wishes a less onerous solution.

OK, then how about "married to a Thai to someone who was, or could be, married under Thai law". Obviously, it is not good enough to say someone is married. As you point out, many people who are married are not eligible for a Non O visa based on marriage.

Based on marriage to a Thai of the opposite gender.

It is possible to make an online appointment. For English speakers, they make it at hard as possible to find the correct page. Open https://qlegal.consular.go.th/. An announcement in Thai obscures the page when first open. Click anywhere on the page and the announcement disappears allowing you to see the appointment system.

So, I guess you would attest that someone who is working and spends his vacation days in Thailand must be a "retiree". If not, and he is not a "tourist", how should he be described? Permanent Thai resident?

Assuming the extensions you have been receiving require the officials to be flexible about financial proof, take a close look at your most recent extension, and look at where it was issued. Until around last October, processing such extensions was possible, but cost substantially more than if you were willing to have your passport sent up country for processing. Since October, all the agents report that they can only process extensions in Bangkok if you can meet all the conditions for the extension, with no need for flexibility on the part of the officials. On a point of information, almost all extensions handled by Bangkok agents have been sent up country for processing for the last several years. This was to allow them to offer as attractive a price as possible.

There are a few visa agents in Bangkok but, at the current time, none of them will actually process visas and extensions in Bangkok itself unless you meet all of the official requirements. They are unable to persuade the officials to use their discretion to be flexible over the requirements. Instead, they send the passports up country for processing at immigration offices where strict adherence to some of the normal requirements can be waived. If your interest is in a Bangkok agent who will take you to Chaengwattana immigration, ensure all the documents are perfect, arrange VIP queuing (no longer important with the appointment system) and generally hold your hand through the process, you might consider Asia Visa Consulting (https://www.facebook.com/asiavisaconsulting/).