What are the requirements for applying for a Non-O retirement visa in Thailand after entering on a tourist visa?

1.

A long-term (1-year) extension is two steps process. You cannot apply for a 1-year extension directly from the visa-exempt or tourist entry.

So, first, you have to apply for a Non-O visa, either at the embassy/consulate outside Thailand OR the local immigration office. When you apply for a visa at the IO, you need funds but the fund doesn't have to be in the bank account for a certain & minimum period.

When you are in Thailand on a stamp from that Non-O visa and you are in the last month of that stamp, finally you can apply for a '1-year extension' for the same reason as your initial Non-O visa. For applying for a 1-year extension, you need to have your funds in your Thai bank account for more than the specified minimum period.

That's why there are two different requirements for your funds for you to stay in Thailand for more than one year.

2.

STV is a Special Tourist Visa, not the same as a Single Entry Tourist Visa. STV is supposed to be one of the temporary measures during Covid chaos, and the STV program is set as ending on 30 September. STV gives you 90 days on entering Thailand and it is eligible for two-time maximum special tourist extensions of 90 days for each. You cannot apply for any other extension or in-country visa from STV entry.

You'll need 800K seasoned in a Thai bank for 2 months prior to applying for a year extension based on being over 50 and 3 months after and it must not drop below 400K for the rest of the year

You need to have the money in a bank account already and be able to show it was transferred from overseas to get the initial 90 day non-O visa.

A tourist visa gets you stamped in for 60 days when you arrive, and an STV gets you stamped in for 90 and has many extra requirements.

The biggest difference to you is you can change a tourist visa to a non-O if you meet the requirements, but an STV cannot be changed inside the country.

In order to apply for a Non-O visa inside Thailand you must have transferred into a Thai bank account in your name a minimum of 800k baht from overseas. There is no seasoning requirement for the initial visa application, that only applies to the following extension

Question 1;

you DO need the 800K baht in a thai bank account in your name only transferred in from abroad when applying at the immigration office for the in country 90 day Non-O visa for 2000baht (it just doesn't have any seasoning requirement).

After you get the Non-O visa the funds need to be seasoned in the account for two months before you apply for your yearly extension for 1900baht.

The funds need to stay in the account for 3 months after the extension is granted and then the balance can't go below 400K baht the rest of the year. You meet those requirements EVERY time for each yearly extension.

Question 2;

A STV <- Special Tourist Visa cannot be used to apply for ANY visa inside the country. it is a come here spend the 9 months that visa allows as a tourist and then leave sort of thing.

You want to get a single entry tourist visa from the thai consulate in the UK using the eVisa website, you want the tourism and leisure choice and you pick single entry. That will stamp you in for 60 days when you arrive and you can extend that by 30 more at the immigration office for 1900baht if you need to