General thumb rule for calculating leave salary is "salary will have to be calculated at rates what the employee would have drawn had he not gone on leave". In some circumstances there are certain different applicability. Say for e.g. 'Field allowance" or "Project Allowance" "Conveyance Allowance (when linked to actual kms travelled)" which is to be paid on actual days on duty/worked in the field/project site on 'pro-rata basis'. In such cases the incumbent will not be eligible when on leave. Therefore pay & allowances which are not linked to actual days of duty/work will have to be considered for payment of salary during leave period. These may include-Basic pay, DA, HRA, City allowance, Medical allowance, Special allowance, Uniform allowance etc.