The determination of an individual’s tax residence is a delicate exercise, combining a review of factual elements in light of different sets of criteria and rules. Most jurisdictions other than the U.S. impose tax solely on the basis of residence. Hence, a definition of tax residence is required. French domestic tax law adopts a single definition of tax residence for personal income and inheritance taxes, relying on several alternative criteria. The matter of residence also can be looked at under a relevant income tax treaty. France has in effect a network of more than 120 income tax treaties. Michaël Khayat, a Partner of the Arkwood Law Firm, Paris, and Edouard Girard, an Associate of the Arkwood Law Firm, Paris, explain the criteria for determining tax residence under French domestic tax law and to resolve a dual resident situation under the O.E.C.D. Model Income Tax Treaty. They then address recent cases under which tax authorities challenged application of an income tax treaty for an individual claiming benefits under a favorable newcomer regime in a treaty partner jurisdiction.