My first year of retirement Extension will expire in February 24, 2017. I don't stay here full time thus had planned to get another visa in USA, but may instead transfer the required funds to secure my retirement Extension. What's the best way to move funds to a Thai bank. Is it acceptable to make a one time transfer?

You can transfer it all at one time. There is no requirement to do it over a period of time. Just be sure you have the 800k baht in the bank 3 months on the date you plan on applying for the extension.

Be sure you transfer the funds as pounds to get the best exchange rate. The rate if you did it in the UK would be lower.

If you have a Bangkok Bank account the least costly way  is to send it through their London Branch.

 

 

3 hours ago, ubonjoe said:

If you have a Bangkok Bank account the least costly way  is to send it through their London Branch.

 

Often true, but not always. My UK bank charges me nothing at all to send international transfers, so even if I had a Bangkok Bank account it would be cheaper for me to use my UK bank to send money from the UK to it. I pay only the Thai bank receiving charge of 0.25% capped at 500B.

 

Some other banks also charge nothing or very little for transfers, so it's well worth checking before deciding.

 

The OP mentions the US but not his nationality. If he is a US citizen then it might be better for him to get an income certificate from the US consul here as as far as I know this is still done based on a simple declaration and would get round the seasoning requirement too.

54 minutes ago, KittenKong said:

 

Often true, but not always. My UK bank charges me nothing at all to send international transfers, so even if I had a Bangkok Bank account it would be cheaper for me to use my UK bank to send money from the UK to it. I pay only the Thai bank receiving charge of 0.25% capped at 500B.

 

Some other banks also charge nothing or very little for transfers, so it's well worth checking before deciding.

 

The OP mentions the US but not his nationality. If he is a US citizen then it might be better for him to get an income certificate from the US consul here as as far as I know this is still done based on a simple declaration and would get round the seasoning requirement too.

 

Which UK bank do you use? 

OP status is not clear as he says first year retirement extension but then says will get another visa in US.  If he now has a multi entry O-A visa and the first year (visa validity) is expiring he should know a new entry before it does gets a new year stay from that entry date.  

 

 

3 hours ago, lamyai3 said:

Which UK bank do you use? 

Several. The one in question is Investec.