The OECD Model Tax Convention contains a complex system for allocating taxing rights between the residence state and the source state. Technically, it would be possible to reduce the number of rules dramatically, but the acceptance of the OECD Model depends to a certain extent on some complexity. The disadvantages of a complex system for allocating taxing rights, however, are evident. The tax treatment of pensions in the OECD Model is an example of such complexity. This article examines the various provisions of the OECD Model which affect the tax treatment of pensions - in particular Art. 19 and its relation to other provisions of the OECD Model. The article concludes that Art. 19 is the cause of many difficulties concerning how to draw the borderline between Art. 19 and the other provisions. One possible solution would be to delete Art. 19 or at least Art. 19(2).