delivered to the customer once it has been shipped, and title and risk of loss have been transferred. For most of the Company's product sales, these criteria are met at the time the product is shipped. For online sales to individuals, for some sales to education customers in the United States, and for certain other sales, the Company defers revenue until the customer receives the product because the Company legally retains a portion of the risk of loss on these sales during transit. If at the outset of an arrangement the Company determines the arrangement fee is not, or is presumed to not be, fixed and determinable, revenue is deferred and subsequently recognized as amounts become due and payable.

The Company records reductions to revenue for estimated commitments related to price protection and for customer incentive programs, including reseller and end-user rebates, and other sales programs and volume-based incentives. The estimated cost of these programs is accrued as a reduction to revenue in the period the Company has sold the product and committed to a plan. The Company also records reductions to revenue for expected future product returns based on the Company's historical experience. Future market conditions and product transitions may require the Company to increase customer incentive programs and incur incremental price protection obligations that could result in additional reductions of revenue at the time such programs are offered. Additionally, certain customer incentive programs require management to estimate the number of customers who will actually redeem the incentive based on historical experience and the specific terms and conditions of particular incentive programs. If a greater than estimated proportion of customers redeem such incentives, the Company would be required to record additional reductions to revenue, which could have a material adverse impact on the Company's results of operations.

Allowance for Doubtful Accounts

The Company distributes its products through third-party resellers and directly to certain education, consumer, and commercial customers. The Company generally does not require collateral from its customers. However, when possible the Company does attempt to limit credit risk on trade receivables with credit insurance for certain customers in Latin America, Europe and Asia and by arranging with third-party financing companies to provide flooring arrangements and other loan and lease programs to the Company's direct customers. These credit-financing arrangements are directly between the third-party financing company and the end customer. As such, the Company does not assume any recourse or credit risk sharing related to any of these arrangements. However, considerable trade receivables that are not covered by collateral, third-party flooring arrangements, or credit insurance are outstanding with the Company's distribution and retail channel partners.

The allowance for doubtful accounts is based on management's assessment of the collectibility of specific customer accounts and includes consideration of the credit worthiness and financial condition of those specific customers. The Company records an