About

Tax Residency Days replays the published day-counting tests that determine tax residency — transparently, for several countries at once, entirely in your browser.

Why this exists

People who live across borders — remote workers, digital nomads, assignees, students — face the same question every year: have I stayed too long somewhere? Most tools online answer a simplified version of that question for one country, hide the arithmetic, and never cite a source. This site exists because the answer should be shown, not asserted: every verdict expands into the exact calculation and points to the official publication it follows.

Methodology

• Pin the source. Each country's implementation is tied to an official publication (IRS Publication 519, CGI Article 4B, LIRPF Article 9.1, TUIR Article 2, Singapore's Income Tax Act, ITAA 1936) recorded on the page and in our sources directory.
• Replay official examples. Before a country goes live, its rule must reproduce the worked examples in the official publications, as automated tests. A country whose tests fail does not ship.
• State the boundaries. Every verdict lists what the calculation does not decide. Day counts are one input to residency, not the whole law.
• Date everything. Pages carry a "verified as of" date. Rules change yearly; pages with stale verification dates are flagged and re-checked each January.

Privacy

The website calculates ordinary inputs in your browser and saves the ledger in local storage, without an account. Optional share links contain the trips and are readable by recipients; opening them sends the URL to our host. The separate AI tool endpoint receives tool inputs for server-side calculation. See the privacy page for details.

Contact & corrections

Spotted an error, or a rule changed and the page hasn't caught up? Corrections are welcome and cited. Contact: [email protected]. Include the page URL and an official source for a rule correction.