Hi @paul9846,
Your tax residency status determines where you pay tax, not your visa status. If you leave Australia temporarily and don't set up a permanent home in the UK, you'll generally remain an Australian resident for tax purposes. This means you'll need to continue declaring your worldwide income, including your pension, in Australia.
If you do become a foreign resident for tax purposes while you're in the UK, you'll only need to declare Australian-sourced income in Australia. The Australia–UK tax treaty sets out which country has taxing rights over different types of income.
Because you may pay tax on the same income in both countries, you can claim a foreign income tax offset in Australia for tax you've paid in the UK. This helps avoid double taxation. To claim this offset, you'll need to have records proving the tax has been paid overseas.
You can use our Determination of residency status – leaving Australia decision tool to work out your tax residency status. This will take between 5 and 10 minutes to complete. Your residency status can change depending on how long you're away and whether you establish a permanent home overseas, so you may need to review it if your circumstances change.