An extension of the standard non-relativistic R-matrix codes is presented which allows for the calculation of total and single differential (with regard to energy loss) electron and positron impact ionization cross sections of atoms and ions. The method uses distorted waves for a “fast” ionizing projectile and an R-matrix (close-coupling) expansion for the “slow” ejected electron. Exchange between outgoing electrons (for electron impact ionization) and positronium formation (for positron impact ionization) is neglected.