For most people, the beginning of fall means the start of a new academic year. For UK personal tax advisers, however, it marks the beginning of the busy season. From this point onward, every day inches closer to the January 31, 2027, Self Assessment filing deadline, and we advisers will not stop reminding ourselves—and our clients—of it. Now is when we encourage clients to start gathering their information and considering their UK filing obligations for the tax year that ended on April 5, 2026.
Tax filing is hardly an exciting topic. It’s usually simply a necessity, if not a nuisance. And navigating the everchanging UK tax system can be complicated for people who have lived here for years, let alone expats who have recently arrived in or left the UK. For more complex UK expat tax circumstances, seeking advice from a qualified tax adviser can be particularly valuable (even though it comes at a cost).
I regularly speak with clients who are unsure whether they need to file a UK tax return or, if not, whether they should, given a potential benefit. Here are four of the most common questions I receive when discussing UK tax return filing obligations—and why, in some cases, filing a return may be in a client’s best interest.
1. I left the UK a year ago, haven’t been back, and don’t have any UK income. I received restricted stock units (RSUs), but my employer already reported and taxed the UK portion through UK payroll. Do I need to file a tax return?
If you are UK nonresident and your only UK-taxable income has already been correctly reported and taxed through UK payroll, you might not need to file a UK tax return.
However, it may still be in your interest to file one. Employers sometimes apply a higher rate of tax to trailing income, including share awards, which can result in more tax being deducted than is ultimately due.
In addition, depending on your circumstances, Overseas Workday Relief may also be available and could further reduce your UK tax liability, potentially resulting in a refund.
So, even where there is no filing requirement, it can be worth reviewing the position to make sure you have not overpaid UK tax.
2. I moved from Sydney to London last year. I only have salary and bonus, both taxed through payroll. I receive company shares, but they just sit in my US brokerage account. Do I need to file a return?
This scenario has more to unpack than it may initially seem: It is exactly the type of situation where a UK tax adviser’s help can be most valuable.
First, the shares may generate dividend income, potentially creating a filing requirement. However, if the individual is likely to be eligible for the foreign income and gains (FIG) regime, qualifying foreign income and gains may be exempt from UK tax, although they still need to be reported.
I would also check whether the client traveled overseas for work, as Overseas Workday Relief may be available.
Finally, the salary, bonus, and share awards may contain a non-UK element that has been taxed through payroll but could potentially be relieved through a tax return.
What looks like a simple everything-is-taxed-through-payroll situation can therefore present several UK tax-planning opportunities.
3. Why do I need to pay additional tax on pension contributions that come from my own pocket?
What matters here is understanding UK pension rules, resolving the potential tax charge, and making changes for the future.
Most people never encounter the pension annual allowance charge because their contributions remain within the annual allowance. However, for higher earners, the allowance can be reduced under the tapered annual allowance rules. The standard annual allowance is currently GBP 60,000, but it can reduce by £1 for every £2 of adjusted income above £260,000, down to a minimum of £10,000 (if your annual income is above £360,000).
If contributions exceed the available allowance, the excess can give rise to an annual allowance charge, effectively taxing the excess at the individual’s marginal rate (45%).
There are further rules, including the ability to use unused allowance from previous tax years, so the position is not always as straightforward as it first appears. If you are in this situation, it’s worth seeking advice before making additional pension contributions.
4. Why can’t I claim a refund for my mortgage, private medical expenses, family with two kids, or my children’s education in the UK like I can in the US?
The UK tax system is generally less generous than some other countries when it comes to personal deductions.
You generally can’t claim mortgage payments, private medical expenses, private school, or childcare fees as deductions. Having dependents or children also doesn’t reduce your UK income tax liability.
Some relief may be available, however. The most common non-employment-related claims I see include Gift Aid donations and qualifying rental property expenses, such as certain administration and maintenance costs.
Understanding the UK expat tax landscape
Your first UK tax return can be a little more involved when you’re new to the UK tax system, particularly if you have recently moved to the UK or have income and assets in more than one country.
Similarly, if you’re leaving the country, UK tax considerations following your departure can be equally complicated.
Considering all there is to understand about the UK tax system, whether coming or going, it can initially seem daunting. However, support is available if you need it. If you would like assistance with your UK expat tax affairs—including determining your filing requirements, preparing your Self Assessment return, or understanding how your overseas income may be treated in the UK—please get in touch.