Which means you do not have to try several times to fill in the online application. You get directly an answer that it is recieved and you wait for the result, if denied you visit Immigration, you do not try again with same details.
Assuming you are not visiting other countries for just a few minutes or hours, apply in the last to visit country at a Thai Embassy for the Single Entry Tourist Visa and safe all the hassle.
So get to Thailand without visa and get 30 days Visa Exempt.
Fly to other countries, apply there for the visa and on return get 60 days based on the visa.
Before travel apply for the Non Immigrant O visa based on being over 50 years of age (retirement) using the on-line application system:
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He will get 90 days of stay when he arrives and show this visa from the Immigration booth at the airport.
Than he can contact the Canadian Embassy, get a affidavit of income and use that to apply after 60 days but before the 90 days ends for the 1 year Extension of Stay based on being over 50 years of age.
Open a bank account in Thailand in your name only and deposit 800.000 Thb. After that you can apply for a conversion of your Visa Exempt Entry into a Non Immigrant O visa and get 90 days of stay.
After 60 days you apply for a 1 year Extension of that stay.
You make sure you deposit each and every month at least 65.000 Thb into that bank account as a foreign deposit and after 12 months but before the 1 year Extension of Stay ends you apply for a new 1 year Extension of Stay using your monthly deposits.
IF you have the 1 year Non Immigrant B visa, which you bought at a Thai Consulate abroad, you can keep on using that Visa until the valid until date. You can even make a border run on the day before the valid until date to get a new 90 day Admitted to Stay.
BUT your work permit has to be cancelled and returned within 15 days of the last day of working at the same Ministry of Labor.
Just to add: The financial requirement is a minimum Thai salary of 40.000 thb a month, shown with the last 3 months of tax and sso payments from you and mentioned staff to get the work permit. Also werk permit copies are needed.
Immigration might ask for more company documents, so best is to pay them a visit before apply for the hand out.
make the copy, tick the box and when all done go back and it will go smoothly.
The visa is valid for 1 year, IF you do a border run as Lloyd described you get 15 months out of this visa. IF you visit Immigration office before the 15 months ends, you can apply for an Extension of Stay based on visiting wife, cost 1.900 Thb, no financial requirements but copies ID's and marriage papers, to get another 60 days.
Which makes a total of nearly 17 months out of this 1 year Multiple Entry Non Immigrant O visa based on marriage with a Thai National.