We present the decomposition of interaction energies in beryllium clusters, Bem-3-6, into a series of nonidentical m-body nonadditivities up to m = 6. We analyse the role of the electron correlation and compare nonadditivities at HF, CASSCF, MP2, CASPT2 and CCSD levels of theory with the reference aug-cc-pVTZ CCSD(T) results. The dominant nonadditivity terms are the three-and four-body. Five and six-body terms are relatively large in Be5-6 clusters, but the total interaction energy of Be-6 is affected only marginally, due to their mutual cancellation. (C) 2013 Elsevier B.V. All rights reserved.