If I retired in Thailand on my Australian pension would I pay tax on this?

This depends on the type of pension that you have. If this is a government pension or civil service pension there are exclusions for tax under the double taxation agreement. If it is a Superannuation, annuity or age pension, then these are assessable income sources if remitted to Thailand if you are a Thai tax resident (180 days or more in Thailand in a calendar year)

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