One way to solve complicated systems of differential equations is the application of operator splitting techniques. The original problem is split into several subsystems that are
solved cyclically one after the other. Naturally, this procedure introduces an error, which is called
splitting error, into the calculations. It is known that if the splitting procedure is applied to autonomous
systems of ordinary differential equations, then the frequently used splitting procedures:
the sequential, the Strang-Marchuk and the symmetrically weighted sequential splittings generally
have splitting errors of order one and two, respectively. In this paper, we show that the order of
the splitting procedures is preserved for non-autonomous problems. The theoretical results will
be verified on numerical test problems.