Stuart Walker

I am a British citizen moving back to the UK from Germany in February 2025, i.e. just before the tax year ends, and I intend to remain in the UK for many years. I've read all of the RDR3: Statutory Residence Test (SRT) page and I want to understand whether once I become a UK tax resident, if beginning of my tax residency be backdated to when I moved back to the UK and started working? For example, I was looking at RDRM11370, "all or part of the 365 day period falls within the tax year", so if I manage to work for 365 days and at least one of those days was in 2024/2025 tax year, then I am a tax resident for that period (assuming also the 3 hour minimum..). I can imagine a scenario where I start working in February 2025 and then work for 365 days, I could perhaps be tax resident also for 2024/2025, but it would only be clear perhaps in 2026. For me the implication is whether or not I will be able to open an ISA on my return to the UK (requirement: UK resident) and whether or not I will be able to use my CGT allowance in the 2024/2025 tax year. I know I will become a UK resident, I just want to understand this period beforehand in the previous tax year.