Which passport to use for a visit to Thailand?

[uzynkotak]

I have an American and a European passport (originally from Europe, live in the US). I'm going to Thailand for a month and both the passports qualify for a 1 month visa free entry. Next year, I'm planning on getting a Thai METV in the US, in my US passport, and spending at least a few months in Thailand. I visited Thailand a few times, never spent more than a month at a time there, never had any problems with overstay, entry denial, etc. The most recent visit was two years ago when I used my US passport. My name is spelled exactly the same in all my documents. I gave my US passport details when I booked my ticket to Thailand for the upcoming one month trip. 

 

I am considering using my European passport to enter Thailand this time. I'm also going to Vietnam where this passport will give me up to 2 weeks visa free (not available for US citizens). Also, if I use my European passport this time and get an METV in my American passport next year, I will be not have too many Thai entry stamps in my US passport.

 

Should I use my European passport to enter Thailand this time? Does it make any difference? Will the Thai border patrol link my name and DOB anyway, and if so, is it possible that using one passport this year and another one next year will increase the chances of being denied entry? I am not trying to dodge the rules or lie to anybody, just want to minimize potential problems in the future given many recent reports of entry denial for no good reason. 

[ubonjoe]

You could use the European passport if you wanted to.

Immigration on entry to the country can link your passports when you enter the country and see all your history on both passports.

If you entered using your US passport you could swap passports to use the European passport for entry to Vietnam. Leave Thailand using your US passport and enter Vietnam using the other one.

[elviajero]

3 hours ago, uzynkotak said:

Should I use my European passport to enter Thailand this time? Does it make any difference? Will the Thai border patrol link my name and DOB anyway, and if so, is it possible that using one passport this year and another one next year will increase the chances of being denied entry? I am not trying to dodge the rules or lie to anybody, just want to minimize potential problems in the future given many recent reports of entry denial for no good reason. 

It is almost certain that your two passports/nationalities will be linked. Once that’s done you full history is available to the IO.
 

Using two passports shouldn’t increase the chances of being denied entry. It’s the combined time spent in the country they take into account.