Britain's tax-residence rules used to be case law and a rough rule of thumb. Since 6 April 2013 they are a flowchart — and almost every box on it is a count of days.
The test that replaced a guess
For decades, whether you were a UK tax resident turned on accumulated court cases and a much-repeated "183 days" shorthand. The Statutory Residence Test (SRT), in force since 6 April 2013, replaced that with a written, three-part test applied in a fixed order:
- the automatic overseas tests — pass any one and you are non-resident;
- the automatic UK tests — meet any one (and no overseas test) and you are resident;
- the sufficient ties test — if neither settles it, residence depends on how many days you spent here and how many ties you have to the UK.
The UK tax year runs 6 April to 5 April, and the count restarts each year. Every test below is read against that window.
What counts as "a day"
The SRT is built from days, and a day has a precise definition. You spend a day in the UK if you are here at the end of it — present at midnight. Leave before midnight and, as a rule, that day does not count.
Two adjustments matter:
- The deeming rule can pull in days you were here during the day but not at midnight. For someone who was UK resident recently and has at least three ties, once they pass 30 such "qualifying days", the rest are treated as days spent in the UK.
- Exceptional circumstances beyond your control can let you disregard some days — but only up to a maximum of 60 days in a tax year.
Even the simple act of counting days, in other words, has edge cases that a hazy memory gets wrong.
The automatic overseas tests
These come first, because passing one ends the enquiry: you are non-resident whatever else is true. The day-count versions are:
- Fewer than 16 days in the UK, if you were UK resident in one or more of the previous three tax years.
- Fewer than 46 days, if you were not UK resident in any of the previous three years.
- Full-time work abroad with fewer than 91 days in the UK and fewer than 31 days on which you worked more than three hours here, with no significant break.
Sixteen days. A single fortnight back in Britain, plus a couple of stray midnights, can be the difference between clearing that first test and not.
The automatic UK tests
Meet any of these — and no overseas test — and you are resident:
- You spend 183 days or more in the UK in the tax year.
- Your only home is in the UK for a qualifying period.
- You work full-time in the UK across a 365-day period.
183 is the number everyone knows. Notice it sits in the second group: by the time you reach it, the answer is usually already decided by the smaller thresholds below.
The sufficient ties test
If no automatic test applies, residence turns on a sliding scale. The more ties you have to the UK, the fewer days you can spend here before you become resident. The ties are a family tie, an accommodation tie, a work tie, a 90-day tie, and — for those who were UK resident recently — a country tie.
The day bands work like this:
| Days in the UK | Resident recently: ties needed | Not resident recently: ties needed |
|---|---|---|
| 16–45 | 4 | — |
| 46–90 | 3 | all 4 |
| 91–120 | 2 | 3 |
| Over 120 | 1 | 2 |
Read the top row: someone with recent UK residence and four ties can become resident on as few as 16 days. The famous "183-day rule" never comes near.
Why the exact number matters
Three things make the SRT reward precision and punish guesswork. The bands are narrow — 16, 46, 91, 120. A "day" can hinge on where you were at a single instant, midnight. And the previous three tax years feed into this year's result, so the record you need stretches back further than one year.
It is the same lesson as the 183-day rule everyone half-remembers: the law rarely hangs on one tidy number, and the count is the part you can actually get right. The UK is only one country, and others define a "day" and a "year" differently — never assume Britain's midnight rule travels.
A statutory test is, underneath, an arithmetic test, and arithmetic needs a record. Countly keeps that record automatically — every country, every entry and exit, counted on your phone — so the number you hand an accountant is the real one, not a reconstruction from memory and stray boarding passes.
General information only — not legal or tax advice. The SRT is detailed and changes; check the current GOV.UK guidance or a qualified adviser for your own position.