A key component to management of harmonic voltage levels in MV and LV distribution systems is the allocation of harmonic emissions to MV and LV customers. The principals of harmonic emission allocations outlined in IEC Technical Report 61000-3-6 are relatively straight forward to apply when both the capacity of the network and the extent of all future load connections are known. However, allocations are made more complex when distributed generation, typically power electronic based, are added to the mix of customer connections. This added complexity is due to distributed generation potentially impacting the hosting capacity of the network, i.e. enabling more customer connections, and the uncertainty for network planners in quantifying the likelihood of future distributed generation connections, given the prolific growth of renewables. This paper introduces a tapered probabilistic approach for network planners to undertake harmonic emission allocations for MV and LV networks which are likely to host significant levels of renewable based distribution generation. The method is demonstrated using a simplified network model.