According to the immigration website, you need 15 days visa validity to convert a TR to a non-b visa. However, this doesn't make much sense to me as last time I did it the non-b was stamped on the same day as I made the application, so why the need for 15 days? And I'm informed that as long as you're not on overstay, your application will be accepted. So if I turned up to immigration with all my documents in order with 3 days left on my visa, would they accept it or would I need to get the TR visa extended by 30 days and then make the application? That would seem completely nonsensical if the non-b was going to be granted on the same day anyway.

The 15 days requirement is needed for all non immigrant visa applications at immigration. It is needed to allow time for your visa application to be approved at the division level of immigration.

You must of applied for your previous non-b before the new rules went into effect a few years ago,

 

21 minutes ago, ubonjoe said:

The 15 days requirement is needed for all non immigrant visa applications at immigration. It is needed to allow time for your visa application to be approved at the division level of immigration.

You must of applied for your previous non-b before the new rules went into effect a few years ago,

 

So what happens these days? Do you make an application and then get an appointment to come back in two weeks?

8 minutes ago, edwardandtubs said:

So what happens these days? Do you make an application and then get an appointment to come back in two weeks?

You will be given a date to return for the visa to be stamped in your passport. Most offices post date the visa stamp to the day you applied and start your 90 day stay.

It seems like it's going to be easier to do a visa run to Laos. Is it still possible to apply for a non-b on the same day you arrive in Laos?

4 hours ago, edwardandtubs said:

this doesn't make much sense

Welcome to Thailand.

12 hours ago, edwardandtubs said:

It seems like it's going to be easier to do a visa run to Laos. Is it still possible to apply for a non-b on the same day you arrive in Laos?

You could apply for a 30 day extension of your tourist visa or visa exempt entry on the same day you apply for the non-b visa unless you have already gotten one.

You could apply for a non-b visa on the same day your arrive in Laos if you arrive at the embassy or consulate before they stop accepting applications at 12am or earlier.

For Vientian you must make an appointment to apply. See: https://thaivisavientiane.com/