We have investigated theoretically the ground state and electromagnetic response of InAs-GaSb type-II quantum dots in the presence of a vertical magnetic field. The ground state is calculated within the Hartree approximation using a 2-band k . p effective mass Hamiltonian to represent the coupling between the two spin-split sets of dot levels derived from the lowest InAs electron subband and the highest GaSb heavy hole subband. The FIR response is calculated within the RPA. We show that the interlayer Coulomb interaction between the electrons and the holes combined with the k . p mixing breaks the generalized Kohn's theorem leading to a complex FIR spectrum. (C) 2000 Published by Elsevier Science B.V. All rights reserved.