I will try to explain in as much detail as possible and somewhat refute what was said in the video from Thai elite visa partner; this story does not take into account FATCA, OECD and CRS automatic and manual data exchange between jurisdictions. I’ll say right away that “loophole” has absolutely nothing to do with it.
1. The case when you receive income for remote work for a foreign company and this company pays you directly for an invoice to a Thai bank to your personal account. This is and always has been taxable if you live in Thailand for more than 180 days a year. And you've clearly paid tax before (or not?).
2. The case when you receive income for remote work for a foreign company and this company pays you into a foreign bank account into your foreign personal bank account. Next, you transfer this money to yourself into your personal Thai bank account. This is subject to tax and has always been taxed if you live in Thailand more than 180 days a year.
3. The case when you receive income for remote work for a foreign company and this company pays you into a foreign bank account into your foreign personal account. Next, you transfer this money to your Thai wife into her personal Thai bank account, as a gift, or to your son or friend or someone else in Thailand. Gift tax begins to apply if you transfer more than 10 million baht to anyone in Thailand during a calendar year, or if you transfer more than 20 million baht to your Thai wife or other close relative. But they will be the ones paying their gift tax. Note that this is a completely different tax, and you cannot gift funds without first paying income tax on them. That is, you can give it as a gift, but then you will still have to pay income tax on the funds brought into Thailand.
However, you initially earned this money and it is considered income. Then you delivered this income to Thailand, no matter to whom, yourself or your Thai wife or son or friend. This is and always has been taxable if you live in Thailand for more than 180 days a year.
But in cases 2 and 3 there is a problem that the Thais cannot in any way determine whether you are transferring savings or earnings, so no one ever paid taxes and simply transferred money to themselves or relatives.
In 2021-22, Thailand connected to the CRS system to automatically receive data on overseas bank accounts. So they will be able to determine this, starting from 2024. It is important. Now they can get this information from your overseas bank. Not all foreign banks/payment systems within CRS operate automatically, some process only manual sent requests from any connected to CRS jurisdictions. The question is whether the Thai tax office will send such a request. There are also separate instruments for the exchange of tax information between countries, not only within the OECD.
I'm just warning you in advance, don't think that you can simply transfer the funds you earned from your personal account in a foreign bank to your personal account or the personal account of your Thai wife, son, your friend, or to someone else's account, even if they live in Thailand for less than 180 days in a calendar year and are not tax residents of Thailand. The main thing is that you live in Thailand for more than 180 days in a calendar year and are a tax resident of Thailand and it is you who transfer your income to Thailand, and for whom this is not so important.
This is taxable income and with Thailand connected to the CRS system and other tax data exchange tools, they will know about the transfers of your money for a particular calendar year from your overseas bank account. There is a slight exception, if you do not have a Thai bank account or you close your Thai bank account, then the tax office in Thailand simply most likely will not be able or will not initiate a request to the CRS system, since you simply do not have a bank account in Thailand and Thailand banks simple no have information about your foreign bank accounts, that is, it is very problematic to somehow do it manually and compare data with the data of the foreign account from which you sent money transfers to a bank in Thailand to the personal account of the Thai wife, son, friend and so on. But if you have always previously sent money from your foreign bank account to your bank account in Thailand, and from 2024 you will send money from the same account, but to the account of your Thai wife, son, friend then the tax office will quickly identify this method of tax evasion.
The last exception is ATM cards. There is a gap here, because you never know what John Doe withdrew money from an ATM in Thailand, and there can be many such John Does, including those who live in Thailand and are tax residents. Yes, technically, Thais can start applying to CRS for all banks from whose cards money was withdrawn, but this is unrealistic at the moment.
In any case, as for pensions, you will be able to provide documents from your foreign bank stating that these are pensions, if the tax office has questions for you.