Worldwide tax once resident, with a four-year exception
Until you are resident under the Statutory Residence Test, the UK generally taxes only UK-source income such as UK rent or UK employment. Once resident, the default is worldwide taxation. The exception is the FIG regime: after at least 10 consecutive tax years of non-UK residence you can claim 100% relief on foreign income and gains for your first four UK-resident years, covering Australian rent, dividends, interest and gains on foreign assets, and you can bring the relieved money into the UK freely. The claim is made year by year on your return and costs you the £12,570 personal allowance and £3,000 CGT annual exempt amount for each year claimed. As a new arriver the ties thresholds are relatively forgiving, but 183 UK days in a tax year makes you resident with no further analysis.
Superannuation: the area to approach most cautiously
Australian super is generally not a UK-registered or UK-recognised pension scheme, so do not assume Australian tax treatment carries across. The 25% UK tax-free lump sum does not automatically apply, and once you are resident HMRC generally views payments from a foreign pension as taxable foreign income, with lump sums less clear-cut than regular periodic payments under the UK-Australia treaty. The FIG regime can help because most foreign pension income is eligible, so drawdowns taken inside your four-year window can be relieved by a valid claim. Very few Australian funds are on HMRC's recognised overseas pension scheme list, so transfers in either direction can trigger UK charges: take joint UK and Australian advice before you draw, transfer or restructure anything.
Australian property, shares and the rebasing myth
There is no automatic CGT rebasing of your Australian assets to market value on arrival: that relief exists only for former remittance-basis users. Your original acquisition cost normally remains your UK base cost, so a gain that has built up over decades can fall into UK CGT at 18% or 24% if you sell after your FIG window closes. The planning point is timing: consider realising pregnant gains before you become UK resident, or inside the four-year window where a FIG claim can relieve them. Australian rent and dividends become UK-taxable once resident unless relieved, with a foreign tax credit under the double tax treaty for Australian tax already paid. Horizon UK Tax Solutions runs pre-arrival reviews and first-year returns for Australians on fixed fees agreed upfront; book a free clarity call at /book before you set your arrival date.