When UK tax on your worldwide income stops
Your UK residence ends when the Statutory Residence Test (SRT) says so, based on your day counts, ties and working pattern, not when you board the plane. For a permanent move, most people become non-resident by working full time overseas for a complete tax year, or by cutting UK days and ties below the relevant thresholds. If you meet a qualifying case, split-year treatment divides the departure year in two, so Australian income earned after you leave falls outside UK tax. You claim it on the SA109 residence pages of your Self Assessment return, and notify HMRC of the move with form P85 if you are not already within Self Assessment.
The trap: UK income and property do not follow you
Becoming non-resident does not switch off UK tax on UK-source income. Rent from a UK property stays taxable in the UK: register under the Non-Resident Landlord Scheme so rent can be paid without tax deducted at source, then report it through Self Assessment. If you sell UK residential property after leaving, Non-Resident Capital Gains Tax applies and you must report the disposal to HMRC within 60 days of completion, even when nothing is due. If both countries treat you as resident, the UK-Australia treaty tie-breaker (permanent home, then centre of vital interests, then nationality, then mutual agreement) decides which wins.
What to do before you fly
Model your SRT position before you go, keep evidence of your Australian home and work from day one, and plan the year-of-departure return with its SA109 pages. Take advice before touching your pension: a transfer into Australian superannuation outside HMRC's QROPS rules can trigger a 25% Overseas Transfer Charge, and most Australian super funds left HMRC's list in 2015. How Australia taxes you as a new arrival, including the temporary resident concession on many work visas, needs confirming with an Australian-registered tax agent. Our moving to Australia guide covers both ends of the move in detail.
