The 183-day rule, on each country's own calendar
Most countries presume you are tax resident once you spend 183 days there within their tax year. The number is nearly universal; the calendar it is measured on is not, and that is where people get caught.
121 of 183 days in Vietnam in its current tax year.
Counted over each country's own tax year, which is not always January to December. Day count is one test among several — permanent home and centre of vital interests also matter.
Saves to this device. No account, no email.
What goes wrong, in order of how often
The tax year is often not January to December
South Africa runs March to February. Mauritius runs July to June. The UK runs 6 April to 5 April. Counting on the wrong calendar produces a confident answer that is simply wrong.
183 days is a presumption, not the whole test
Permanent home, centre of vital interests, family and habitual abode all matter too. You can be treated as resident on far fewer days, and treaties decide which country wins when two both claim you.
Leaving one country does not settle where you are resident
Deregistering at home does not automatically make you non-resident, and being under 183 days everywhere does not make you resident nowhere. Both assumptions are common and both are expensive.
Questions people ask
Can I be tax resident in two countries at once?
Yes, and it happens often. Double tax treaties contain tie-breaker rules to allocate residence between them: permanent home, then centre of vital interests, then habitual abode, then nationality.
Does this app tell me where I am tax resident?
No, deliberately. It tells you how many days you have recorded in each country and what that country's published threshold is. What follows from that is a question for a qualified adviser, and this is the document to bring them.
This rule is not the only one counting your days
The same trips are measured by every other rule you are subject to, and the counting conventions contradict each other — Schengen counts your arrival day, the US 330-day test does not. Driftly runs them all against one trip history.
- The Schengen 90/180 rule, counted properly
- The 330-day physical presence test, counted from your real trips
- The UK Statutory Residence Test, one step at a time
Driftly reports your recorded day counts against published thresholds. It does not determine your visa or tax status — confirm both with official sources or a qualified adviser.