Predicted z = 0–2 WISE colours of AGN/galaxy composite SEDs for our three-band AGN wedge. The AGN fraction is defined between 1 and 10 μm. The star-forming templates represent the ULIRG IRAS 22 491 (square; Polletta et al. ), the starburst M82 (star; Polletta et al. ), a normal star-forming spiral galaxy (triangle; Dale et al. ) and an elliptical galaxy (circle; Polletta et al. ). The large symbols mark each family of purely star-forming templates at z = 0. The AGN template is the type 1 quasar template of Polletta et al. (). Additional extinctions of A_V =0 - 2 and 0 - 20 are applied to the star-forming and AGN components, respectively. Our MIR AGN selection wedge and power-law locus are the thick solid and dashed black lines, respectively. The power-law locus is defined from α = −0.3. The colour tracks of purely star-forming galaxies would enter our selection wedge at z >rsim 1.3. At such redshifts, however, most galaxies are too faint to be detected at the relatively shallow 12m flux density limits.