—GAAP does not require any specific format.  Common formats:

A.  Multiple-Step Income Statement—shows details of net sales and other costs and expenses. Has three main parts:

B.   Single-Step Income Statement
Lists cost of goods sold as another expense and shows only one subtotal for total expenses, one subtraction to arrive at net income.

C.  Classified Balance Sheet—reports merchandise inventory as a current asset, usually after accounts receivable (use liquidity order).