the requirements on how to "change" from the tourist visa or from a visa-exempt entry, to the initial "90-days Non-Imm-O Family Dependent Visa", are described in the .pdf under number 8 of the Immigration website regarding the "change of visa type" . . . . print it and take it to Immigration, the requirements are listed both in Thai and English and if you are lucky, Immigration is willing to accept your son doing the "change of visa type" . .

while your 90-days Non-Imm-O Family Visa is a done & dusted things, because you are married to a Thai husband, you son has no family connection to your husband. That's why he only can apply for a 90-days Non-Imm-O "dependent" Visa based on being the son of somebody on a Non-Imm-O Family Visa. Normally he could do the "change of visa type" from a tourist visa to the 90-days Non-Imm-O Dependent Visa on Immigration inside Thailand. However we are aware that some Immigrations won't touch the "change of visa type" process not even with a pair of tweezers. The Immigration who turned you down are one of these Immigrations because they are unsure which are the requirements. . . these are listed under Number 8 on this Immigration website .. . . . But please be aware that this Non-O Visa is limited to children only until the age of 20 . . . . . . Your problem is how to change your location and find an Immigration who is willing to accept it

@Stephen ********

as your British embassy does not certify your income, there is no way around the requirement to transfer a minimum of 400,000 THB into your Thai bank account as soon as you have entered Thailand on a 90-days Non-Imm-O Family Visa, and the money needs to have been sitting in the account for a minimum of 2 months on the day you apply for the "1-year stay permit extension"

@Incognia *********

the agent I know in Pattaya offers this service for BOTH licenses for 7000 Baht . . . I am very sorry for you if you paid an inflated price of 20,000 Baht

@Drew ****

. . . sure, he could do it by himself . . . . I do it by myself since 24 years, but this is advice for a complete newbie, he'd be better off with the help of an agent, it's only 5000-7000 Baht

if you are in Pattaya, visit an agent. They take your hands and lead you through the process really easy . . for something like 5000 to 7000 Baht

you should get an insurance with a two years coverage, because only then you can get into the "second year" of a 365-days Non-Imm-O/A Visa by doing a border-bounce shortly before the visa validity expires . . . . . .and keep in mind, if you go from the first year of the visa and after the second year, to the "1-year Extension of Stay Permit", Immigration will not accept a foreign insurance any more. From the "1-year extension" onward, only a tgia-listed Thai private insurance will be accepted

@Mark *******

There is no guarantee . . . . . if you had more than 180 days "touristic stays" within a recent 365-days period, they will probably pull you aside and interogate you. Regardless if you have a tourist visa or not. And only THEN it would be wise to have the famous three proofs at hand

@Theo *******

you are a Dutch citizen, so your embassy in Bangkok still issues the income affidavit for you. Apply for the Non-Imm-O visa as many Immigrations want to see that you actually have a Thai bank account into which you transfer some money coming in from abroad, despite your income affidvit being sufficient for the financial proof to apply for the 1-year extension of the stay permit based on retirement

@Marc *******

they might have said "calendar year" but actually this is bad English, what they mean is "per one year" or "per 365 days" which is the way visa-exempt stays as a total get calculated