Steel profiles with slightly tapered cross section sides are not uncommon in older structures. The steels are often inhomogeneous and the fracture toughness varies across the thickness. In this project, the geometry of the standard three point bend specimen (ASTM E-1820) is modified to allow full thickness testing of tapered samples. The part of the project reported here deals with the J-integral of the modified specimen. The J-integral is calculated analytically and numerically with the finite element method for a linear and a non-linear material model and different specimen cross section proportions. A simple, single test fracture toughness evaluation procedure is proposed.