Membership dues are the primary source of revenue that the local will receive. It is the prediction of how strong the membership is determined to be in the foreseen period. If there is a downside it will come from exaggerating this number. The budget can always be revised in an upward direction. Having to make cuts in expenditures because revenues are bit lower than projected can be painful. While there is only one major source for income, remember that there are other hidden sources for additional resources.