DoubleTaxation

Lists the 12 versions of DoubleTaxation. Each version is written for taxpayers of one home state (in its language) and compares it with 20 other countries. Call this first if you are not sure which version fits the user.

Takes no parameters.

Lists the countries that can be checked against the home state of a version: whether a tax treaty is in force (title, dates, link), whether per-income treaty rules and tax burden data exist, plus the allowed citizenship options and years for check_residency.

Determines the person's tax residence between the version's home state and another country, step by step. Without all answers it returns status "needs_answer" and the next question (id, text, options); ask the user and call again with all answers collected so far. When complete it returns status "done": the conclusion with reliability %, how each law treats the person, the treaty tie-breaker, where and which taxes apply, next steps (certificate of residence, resident / non-resident obligations, steps when leaving), exit tax and the year of the move (with "move"), what the result does not cover, the legal basis (norms with links) and court practice, optional per-income-type rules, the disclaimer and a link to the same result on doubletaxation.app. Texts are in the language of the version.

Income tax and social contributions on an annual salary in one or more countries (OECD Taxing Wages method: single person, no children, full-year employee). Returns net pay, personal rate, tax wedge and marginal rate, sorted from lowest to highest personal rate. For up to 3 countries also the line-by-line breakdown, special tax regimes for individuals (e.g. for newcomers), assumptions and official sources.

Counts days of stay per country from the trips the user provides (country, from, to) under each country's own counting rule (calendar year, tax year, any 12 months, US substantial presence test, continuous stay): days in the counting period, the day threshold for tax residence and its legal source, the date it was reached or how many more days are needed, and Schengen 90/180 days used. The day of arrival and departure counts in both countries. It does not track anyone: it only counts the trips passed in, and they are not stored.

What to do once the tax residence is known (the same blocks as under the result on doubletaxation.app and in check_residency "done"): how to get a certificate of residence, obligations of a resident (returns, deadlines), obligations and options of a non-resident with income from the other state (treaty relief forms, refunds), U.S. citizen obligations, steps when leaving the state, the exit tax, how each state treats the year of the move, and what the conclusion does not cover. Each step has the authority, form, link and legal norm. Texts are in the language of the version.

Whether a country levies an exit (departure) tax on individuals who give up tax residence: who pays and on what (assets, thresholds, prior residence period), deferral or relief (e.g. moving within the EU/EEA), the legal norm with a link and the date checked.

Special and preferential tax regimes for individuals (newcomers / impatriates, employees, self-employed, investors, pensioners) in 21 countries. Filter by country, kind, status and free text. Returns per regime: official name, who it is for, the benefit, duration, how to apply, limits and risks, status (open, closed to new entrants, only for existing participants, starts later), the legal norm with a link and the date checked.

Tax and contributions on a business profit for each legal form available to a resident of one country (sole proprietor under the different tax systems, own company paying out dividends or keeping the profit): total, what remains, rate, line items, why a form is unavailable (e.g. revenue limit), conditions, legal norms, assumptions and sources. Reference activity: IT / consulting services for business clients. Same calculation and ranking as doubletaxation.app; an estimate, not tax advice.