At the first regular Council meeting of each quarter (unless requested more often by the Council), the Treasurer shall submit to the Council, data showing the relation between the estimated and actual income and expense to date; and if it shall appear that the income is less than anticipated, the Council may reduce appropriations, except amounts required for debt and interest charges, to such degree as may be necessary to keep expenditures within the cash income. If the revenues exceed the amounts estimated in the budget, the Council may make supplemental appropriations if all six of the members of Council affirmatively approve the supplemental appropriations; otherwise, excessive revenue shall be carried forward as surplus to the next fiscal year.