Question 

Can I fly in on a retirement visea that only has 2 weeks on it until it expires? 

I plan to renew once there

Yes.  You can do your extension on the day of expiry (though it's not recommended and providing it's not a government holiday on that day).  Try to renew ASAP as soon at you arrive as you have a 2 week window to get it sorted.

 

Yes.....however.

If the visa you are referring to is a non O retirement and you plan on obtaining a 12 month extension you would not have time to apply for extension.

Immigration requires 15 days remaining.

 

OP, do you actually have a visa or an extension with a reentry permit? 

10 minutes ago, DrJack54 said:

Yes.....however.

If the visa you are referring to is a non O retirement and you plan on obtaining a 12 month extension you would not have time to apply for extension.

Immigration requires 15 days remaining.

 

OP, do you actually have a visa or an extension with a reentry permit? 

Really, i never knew that. So you can't renew a non O visa extension unless it's more than 15 days before the expiry date? That's not what Almudena says above.

19 minutes ago, Henryford said:

Really, i never knew that. So you can't renew a non O visa extension unless it's more than 15 days before the expiry date? That's not what Almudena says above.

I was incorrect. Brain fade.

You need the 15 days if applying for a non O in Thailand.

He is applying for extension.

Can apply up till day of expiry.

???? Sorry

Assuming you have a re-entry permit to protect an extension of stay based on retirement, the immigration official at the airport will probably give you a choice between using the re-entry permit (to resurrect your Non Immigrant permission to stay) or stamping in visa exempt. Make sure the official adopts the option you want. You will probably be unable to change it later if the official gives you a fresh visa exempt entry.