Germany

Tax residency in Germany is established by the jurisdiction's headline test^[1]: physical presence of more than 183 days in a rolling twelve-month period, supplemented by registered home in germany or 183+ days. Spouses and unemancipated minors are typically presumed to share the residency of the principal earner unless rebutted.

Once resident, any special regime is not automatic. Most jurisdictions require a formal registration with the tax authority within a defined window following arrival, together with proof of qualifying activity and a lookback period of prior non-residency. Late registration forfeits the regime for the year in question and, in some cases, for the entire benefit window.^[2]

The common pitfalls are predictable. Treaty interaction with the home state can override the local regime where the home jurisdiction asserts primary taxing rights — most relevantly, United States citizens remain subject to US federal tax on worldwide income, with foreign-tax-credit relief but no escape from the higher of the two bills. Activities undertaken before registration is approved may also fall outside the regime entirely.^[3]