Why do you have to project the financial statements without the impact of debt prior to building the debt schedule?

In order to calculate the cash flow available for debt repayment, we have to project the income statement and cash flow statement. Initially, we exclude debt items, such as interest expense on the income statement and debt repayments on the cash flow statement, since we need the debt schedule to populate these items. After calculating the cash flow available for debt repayment, we can then build the debt schedule as the repayments will drive the balance of debt. Then we can calculate interest expense and link the interest expense to the income statement, debt repayments to the cash flow statement, and debt to the balance sheet.