Yes but you there is a provision that provides an exception.
Exception for small business taxpayers. Inventory Pub 538
If you are a small business taxpayer, you can choose not to keep an inventory, but you must still use a method of accounting for inventory that clearly reflects income. If you choose not to keep an inventory, you won’t be treated as failing to clearly reflect income if your method of accounting for inventory treats inventory as non-incidental material or supplies, or conforms to your financial accounting treatment of inventories. If, however, you choose to keep an inventory, you generally must use an accrual method of accounting and value the inventory each year to determine your cost of goods sold in Part III of Schedule C.
Treating inventory as non-incidental material or supplies.
If you account for inventories as materials and supplies that are not incidental, you deduct the amounts paid to acquire or produce the inventoriable items treated as materials and supplies in the year in which they are first used or consumed in your operations.
