The 180 days are calculated as a rolling period which you can count backward from your entry or exit date in the Schengen. Basically, count back 180 days and see how many of those days you've spent in the Schengen zone; if you're over 90 days, you've broken the 90/180-day rule.

In 2026, the 180-day rule typically refers to one of two major contexts: Schengen Area travel or tax residency. For travelers to the European Schengen Area, it is a "rolling window" rule: you can stay for up to 90 days within any 180-day period. This means you look back 180 days from any day of your stay to ensure you haven't exceeded 90 days of presence. It is no longer a fixed calendar year calculation, making digital tracking apps essential for frequent travelers. In a tax context, many countries (including the U.S. and India) use a similar 180-day or 183-day threshold to determine tax residency. If you spend more than 180 days in a country during a tax year, you are often deemed a resident for tax purposes, making you liable for taxes on your global income in that jurisdiction.