Amazon.com, Inc., provides the following explanation of its revenue recognition policies in its \(10-\mathrm{K}\) report.

We offer Earth's Biggest Selection and seek to be Earth's most customer-centric company for three primary customer sets: consumer customers, seller customers and developer customers. In addition, we generate revenue through co-branded credit card agreements and other marketing and promotional services, such as online advertising.
We recognize revenue from product sales or services rendered when the following four revenue recognition criteria are met: persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the selling price is fixed or determinable, and collectibility is reasonably assured. Additionally, revenue arrangements with multiple deliverables are divided into separate units of accounting if the deliverables in the arrangement meet the following criteria: the delivered item has value to the customer on a standalone basis; there is objective and reliable evidence of the fair value of undelivered items; and delivery of any undelivered item is probable.
We evaluate the criteria of Emerging Issues Task Force (EITF) Issue No. 99-19, Reporting Revenue Gross as a Principal Versus Net as an Agent, in determining whether it is appropriate to record the gross amount of product sales and related costs or the net amount earned as commissions. Generally, when we are the primary party obligated in a transaction, are subject to inventory risk, have latitude in establishing prices and selecting suppliers, or have several but not all of these indicators, revenue is recorded gross. If we are not primarily obligated and amounts earned are determined using a percentage, a fixed-payment schedule, or a combination of the two, we generally record the net amounts as commissions earned.
Product sales and shipping revenues, net of promotional discounts, rebates, and return allowances, are recorded when the products are shipped and title passes to customers. Retail items sold to customers are made pursuant to sales contracts that generally provide for transfer of both title and risk of loss upon our delivery to the carrier. Return allowances, which reduce product revenue by our best estimate of expected product returns, are estimated using historical experience. Revenue from product sales and services rendered is recorded net of sales taxes. Amounts paid in advance for subscription services, including amounts received for Amazon Prime and other membership programs, are deferred and recognized as revenue over the subscription term. For our products with multiple elements, where a standalone value for each element cannot be established, we recognize the revenue and related cost over the estimated economic life of the product.
We periodically provide incentive offers to our customers to encourage purchases. Such offers include current discount offers, such as percentage discounts off current purchases, inducement offers, such as offers for future discounts subject to a minimum current purchase, and other similar offers. Current discount offers, when accepted by our customers, are treated as a reduction to the purchase price of the related transaction, while inducement offers, when accepted by our customers, are treated as a reduction to purchase price based on estimated future redemption rates. Redemption rates are estimated using our historical experience for similar inducement offers. Current discount offers and inducement offers are classified as an offsetting amount in "Net sales."
Commissions and per-unit fees received from sellers and similar amounts earned through Amazon Enterprise Solutions are recognized when the item is sold by the seller and our collectibility is reasonably assured. When we are responsible for fulfillment-related services, commissions are recognized when risk of loss and title transfer to the customer. We record an allowance for estimated refunds on such commissions using historical experience.

\section*{Required}

a. Identify and discuss the main revenue recognition policies for its two primary sources of business revenues.

b. Identify and describe at least three revenue recognition issues in a business such as Amazon.