The predicting ability of Mulliken-type formulae in estimating the charge-transfer (CT) excitation energy in "push-pull" donor-bridge-acceptor (D-B-A) systems is evaluated systematically by tailoring the length of an oligoenic spacer bridge separating an N, N-dimethylanilino (DMA) donor and a dicyanovinyl (DCV) acceptor. In order to achieve satisfactory agreement with time-dependent density functional theory (TDDFT) values, the D...A distance and charge separation inside the D-B-A system are replaced with rigorously calculated "effective" values, while using "superdonor-superacceptor" energetics. The proposed modified Mulliken formula has the potential to be of significant assistance for cases when direct TDDFT calculation of the CT state is unfeasible. (C) 2016 Elsevier B.V. All rights reserved.