The authors present a 40 Gbit/s system model with standard forward error correction (FEC), high polarisation mode dispersion (PMD) and prechirped carrier-suppressed return-to-zero (CS-RZ) format. An approach to evaluation of the system performance is proposed for investigating the coding gain and transmission penalty of standard FEC. The numerical simulation results show that the interaction of the second-order PMD with nonlinearly induced chirp can improve the performance of FEC in some cases.