A modal decomposition of 3D current sources is introduced in the finite integration technique (FIT) discretisation scheme for the solution of eddy-current testing problems in rotationally symmetric work-pieces. The original 3D problem is reformulated in this way in calculating the vector magnetic potential profile on the ρ – z plane for a number of angular modes. The interest of such decomposition relies on the simpler and conformal discretisation of the work-piece, the reduction of the numerical noise, as well as the smaller size of the linear system, which allows the simultaneous treatment of different probe positions.