Article 39 EC (now Article 45 TFEU) precludes national legislation such as that at issue in the main proceedings, pursuant to which a non-resident taxpayer who receives all or almost all of his income in a Member State during the first three months of the tax year and then moves to another State, where he takes up new employment, cannot choose to be subject consecutively to the regimes applicable to resident and non-resident taxpayers in the course of that year, and therefore deduct mortgage interest related to a personal dwelling attributable to those first three months, if that option is available for a taxpayer who resides and works in that Member State during the first three months of the tax year and then moves to another State to take up new employment for the remainder of the tax year. The circumstance that the non-resident taxpayer has gone to live and work in a non-Member State rather than a Member State during the course of the tax year has no bearing on the answer to Question 1.