Budgetary slack is the deliberate under-estimation of budgeted revenue or over-estimation of budgeted expenses. This allows managers a much better chance of "making their numbers," which is particularly important for them if performance appraisals and bonuses are tied to the achievement of budgeted numbers.Budgetary slack may also occur when there is considerable uncertainty about the results to be expected in a future period. Managers tend to be more conservative when creating budgets under such circumstances. This is particularly common when creating a budget for an entirely new product line, where there is no historical record of possible results to rely upon