It wouldn't take me long to figure out if I wanted to spend 1,900 baht or 30,000 but I get that people are different and some are willing to pay extra for the convenience. The only caution I would make about using an agent is to use an agent that is going to use your immigration office (not some other immigration office where you don't live because they "know" someone at the other office) and that is going to help you open a bank account and actually put your 800,000 baht in your account for the required time, rather than use hocus-pocus to make it appear that you have satisfied the financial requirements when you haven't. The reason for doing it by the book, but with help, is that when you decide to not use that agent in the future (because you finally figured out that 1,900 is a lot less expensive than 30,000) you want to be able to make that decision. You don't want to have to deal with that agent forever because of the corners that were cut on your behalf. You don't want to get into the situation where now you want to go straight but the gang won't let you.
Michael Potts there may not be anything official about it but banks are very reluctant to open accounts for people who are here on anything less than a long-term visa (90 days). Banks are reluctant to open accounts for Americans and you can thank FATCA and other heavyhanded tax policies of the US government for that. Even with a Non-O it can be difficult. Try and try again. You may need to get a letter from the US Embassy Bangkok stating that you're a US citizen, displayed a real passport, and live at the address you indicate. Cost $50. If all else fails an agent can usually help you open an account. It helps if they know you're going to be depositing 800,000 baht into the account and largely leave it there (which they may realize if they understand it's for a retirement extension of stay).
If you are going to pursue retirement extension and dependent extension the secondary one of you (the one married to the primary) has to obtain their Non-O outside of Thailand (at least this is the case in Phuket). In other words, the secondary one would need to obtain a Non-O while in Malaysia from the Thai embassy. This is important because while people can typically get a Non-O in Thailand, to take advantage of the piggybacking, the secondary must have entered Thailand with a Non-O, otherwise, they can't piggyback in this manner.
Of course, you can both apply for Non-O in Malaysia and make the work in Thailand a little more straightforward.
Get the tourist visa (60 days). In Thailand open a bank account and transfer the 800,000 baht equivalent into a Thailand bank account (using Wise, SWIFT international wire, or other means). Apply for a Non-O visa for purpose of retirement at your local immigration office and receive a Non-O visa good for 90 days. Let season in account for 2 months, then as soon as possible apply for retirement extension at immigration.
You reference us. If that is you and your spouse, then one of you can get the retirement extension and the other can get a dependent extension based on the one getting the retirement extension. The advantage of this is that only one of you has to have the 800,000 in the bank. The other would have no financial requirements but would have to show marriage to the primary person.
This is the best way of getting on an annual retirement extension bandwagon based on a Non-O. Such extensions, unlike those based on a Non-OA (the A is significant), do not come with ongoing health insurance requirements using immigration-approved Thai insurance companies (400,000 outpatient/40,000 inpatient).
On consideration is that you don't want your branch to be too far from where you live because in Thailand a surprising number of things are required to be done at your home branch and can't be done at other branches of the same bank.
One other thing, apply near the end of your current permission to stay so you don't lose days because your first covid extension is very likely to start from the day you apply not from the day your current permission to stay ends. Follow-on covid extensions should start from when the previous covid extension ends so you can go apply for those earlier if you want without fear of losing days.
Think it needs to be one of these companies, one of which is Pacific Cross.
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You may be able use other insurance but it requires you to get your insurance company to sign a statement promising that they cover the requirements demanded by Thailand, not an easy prospect.