Can I enter Thailand on a 30-day visa exempt and then apply for a Non-Immigrant O visa and a one-year extension?

Unfortunately while you can come here, get your 800K baht banked, apply for your Non-O 90 day visa, then the year extension sadly your wife cannot get a Non-O visa inside the country based on marriage to someone on a retirement visa/extension.

They just don't issue in country Non-O visas for that reason.

That's why people are saying see if you can BOTH get 90 day Non-O visa's from the consulate in your country BEFORE you come here.

Otherwise she's gonna be stuck visa wise, and need to wait until you get thru the whole process (90 day Non-O and year extension) before she can go to Penang to get a 90 day Non-O visa on her own as "trailing spouse" of a retiree..

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AND another post

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If you use the search 🔍 tool top of the forum page

ENTER the words TRAILING SPOUSE

CLICK on it and all posts about it will pop up to read the posts and replies of others.

Here's a Post to read... mentions TRAILING SPOUSE

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I suggest you get the Non O Visa as a retiree in Singapore. That gets you 90 days STAMP on arrival into Thailand. With time to visit your local Thai Immigration office and ask for their list of requirements for the one year extension of stay as retired.

Your wife is not age 50, so I suggest that she get a SETV single entry tourist visa and upon arrival she will be stamped in for 60 days and can get one 30 day extension of stay at Thai immigration office for 1900 Thai baht.

When you get the One year extension of your stay as a retired in your passport, she can go to a Thai Embassy or Consulate outside of Thailand that will issue her a Non O Visa as TRAILING SPOUSE.

Also Suggest you ask your Thai Embassy in Singapore if they would issue your wife a Non O Visa as a TRAILING SPOUSE?

If they will, then that simplifies your actions when you both are in Thailand.

You would apply for a 90 day Non-O visa based on being over 50 at the Thai Embassy in Singapore and your wife would apply for a 90 day Non-O visa based on being married to someone who is on a "retirement" visa (called trailing spouse or piggy back)

You'd both come in and get stamped in for 90 days, you'd get the 800K baht transferred in and let it season the 2 months required to apply for the year extension and then once you get your year extension your wife gets a matching one based on being your spouse (doesn't matter how old she is)

Keep in mind you BOTH need to get the visas in the Singapore before you wing your way here because while you could come here on a tourist visa and then get a Non-O based on being over 50 your wife cannot get an in country Non-O for being the spouse. She would have to enter Thailand as I first suggested with the SETV single entry tourist visa... then when you got your One year extension of stay in Thailand, she would have to go to a Thai Consulate like Penang or Savannakhet that will issue her a Non O Visa as TRAILING SPOUSE.

Yes you can but you will need 800k in a Thai bank account in your name for the application (seasoned for 2 months in some Immigration Offices) unless your Embassy does the income affadavit.

Yes, you can do that. Many do exactly the same.