Bulgaria

Tax residency in Bulgaria is established by the jurisdiction's headline test^[1]: physical presence of more than 183 days in a rolling twelve-month period, supplemented by 183+ days or center of vital interests. 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]