§ Tax

Calendar year

also called Jan to Dec year

The twelve months from 1 January to 31 December, the default clock most people assume every deadline runs on.

Right, in plain English

The calendar year is simply the run from the first of January to the end of December, the clock most of us assume every deadline follows. Many countries, though, do not line their tax year up with it, so a day count or a filing deadline can land on dates you would not expect. Assuming the tax year matches the calendar year is a classic way to miscount your days and stumble into a residency threshold.

You track your days in a country from January onward, sure that is when its tax clock resets. Its tax year actually starts on a different date, so your count is measured against the wrong window, and you drift over a residency threshold you thought you had comfortably avoided.

Why it matters

Many countries do not run their tax year on the calendar year, so a day count or a filing deadline can fall on dates you do not expect. Assuming the tax year equals the calendar year is how nomads miscount their days in a country and trip a residency threshold.

Not to be confused with

The difference is the whole point, so here is each one in a line.

The clock a tax year runs on · 2 terms

A tax year is the twelve-month period a country uses to work out income tax, which does not always match the calendar year of January to December that people assume.
Split-year treatment is the rule that divides the year you arrive or leave into resident and non-resident parts so you are not taxed as a resident for the whole of it.

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