Seasonality payments for milk are intended to encourage milk production in the months July to September, and to discourage production from April to June. Summer calving to match this pattern of production is not popular as the margins achieved on farms are generally poorer than for cows calving in autumn and winter. The reasons for the poor margins appear to be lower lactation yields due to late season grazing coinciding with peak yields, and high concentrate intakes due to the long feeding period from summer to the following spring. This study aimed to develop profitable systems of calving in the summer.