Is it correct that the investment capital gains percentage would be the percentage used against any remittance to Thailand. If I remitted 1 million baht annually to Thailand and my capital gains for that year were 6% would I only pay tax on 60000 baht? Given the first 150000 baht is tax exempt would this imply I pay no tax?

There are many factors here such as if you are a Thai tax resident (180 days or more) and what type of structure you hold. If it is an investment account and you sell assets and transfer to Thailand, then you are liable for the percentage capital gains on the investment. You need to check the DTA to see how your asset is treated.You may find our webinar on the Thailand-Australia Double Tax Treaty useful; you can watch it here. 

You may find our webinar on the Thailand-Australia Double Tax Treaty useful; you can watch it here.