High resolution neutron powder diffraction has been used to study the charge states and spin order in the A-site-ordered perovskite LaCu3Fe4O12. This undergoes a first-order phase transition between ubic Im-3 structures with charge distributions LaCu33+Fe43+O12 and LaCu32+Fe43.75+O12 at T-CT approximate to 400 K. Bond valence sums confirm that these charge states are adopted in the two phases, and there are no substantial valence fluctuations near the charge transfer transition. G-type antiferromagnetic order of B-site Fe3+ spins is observed in the low temperature phase LaCu32+Fe43.75+O12 and the ordered moment at 50 K is 4.0 mu(B). Magnetic moment is absent at the A'-site Cu3+ cation. The thermal evolution of the ordered moment enables an intrinsic T-N' approximate to 600 K to be estimated, although the actual upper limit for the spin order is TCT. No long range magnetic ordering was found in the high temperature phase, LaCu32+Fe43.75+O12, showing that any ordering transition for this regime has T-M < T-CT.