Viability assessments are financial appraisals submitted to LPAs by developers, that establish whether a site is viable by examining whether the value likely to be generated by the development is more than the cost of developing it, including ‘suitable’ profits for developers. Planning practice guidance states that, for the purposes of plan making and for individual negotiations, a profit margin of 15% to 20% may be considered suitable. Developers can submit a viability assessment alongside their planning application.30 The Department wrote to us after the session, stating that it does not hold any analysis or data on LPAs’ use of the profit margin assumption, because it is important for viability judgements to be informed by engagement between the relevant parties and to reflect local circumstances.31