At the beginning of each quarterly period during the fiscal year, and more often if required by the township board, the supervisor or the township superintendent, as the case may be, shall submit to the township board data showing the relation between the estimated and actual income and expenses to date; and if it shall appear that the income is less than anticipated, the township board may reduce appropriations, except amounts required for debt and interest charges, to such a degree as may be necessary to keep expenditures within the cash income.