From the trial balance all the income and expense items are transferred to the income statement. Further, certain other items are also adjusted before transferring the balances. Consider rent. Now, rent becomes payable at the end of a month. Therefore, following the accrual principle the accountant posts the rent as payable outstanding and adds this amount to the rent expense. The rent payable appears as current liability in the balance sheet and squared off when the actual payment is made.

Similarly, insurance payments are made annually. But, they would not match the accounting year. On the date of the preparation of final statement, there could be some months of insurance remaining prepaid. This amount is deducted from the expense and shown as current asset in the balance sheet. It becomes expense for the next accounting period.

The excess of income over expenses represents profit while the reverse scenario would mean loss. Profit adds to the equity or owners' capital while loss erodes the same. In effect, profit means the assets have increased while liabilities have decreased. Loss means assets have decreased and liabilities have mounted.

To find out the exact position of assets and liabilities, the accountant prepares the balance sheet. Although one would know whether the business made profit or loss or the value of assets and liabilities have increased or decreased, there is a need for a statement that gives complete information about how the financial position was achieved. The Cash Flow statement serves this purpose.

The basic rationale behind the cash flow statement is that all operations of the business are connected with receiving and paying cash. This is also called the cash-to-cash cycle. The firm buys inventories, sells them, incurs expenses and pays off the dues. So, there is always a parallel run between the firm's debtors and creditors. There are also transactions like fresh infusion of capital, paying off loans and making investments.
Therefore, to get the correct picture about how the firm's operations and other non-operative items contributed to the changes in financial position, the cash flow statement is useful.

The starting point for the cash flow statement is the balance of cash at the start of the year. There are three segments in the cash flow statement: Operating, Investing and Financing. For the first segment, we knock off non-cash charges like depreciation and loss on sale of assets to derive the operative profit in cash terms. We also adjust the net increase or decrease in all current assets and liabilities except cash. In the second segment, we include the investments in fixed assets or financial instruments. In the third segment, we show the dividend or withdrawal of capital. The net effect of all the three segments is adjusted with the opening cash balance to get the closing cash balance.