Even when specific customer accounts haven't been proven uncollectible by the end of the reporting period, bad debt expense properly should be matched with sales revenue on the income statement for that period. Likewise, since it's not expected that all accounts receivable will be collected, the balance sheet should report only the expected net realizable value of that asset. So, to record the bad debt expense and the related reduction of accounts receivable when the amount hasn't been determined, an estimate is needed. In an adjusting entry, we record bad debt expense and reduce accounts receivable for an estimate of the amount that eventually will prove uncollectible. If uncollectible accounts are immaterial or not anticipated, or it's not possible to reliably estimate uncollectible accounts, an allowance for uncollectible accounts is not appropriate. In these few cases, any bad debts that do arise simply are written off as bad debt expense at the time they prove uncollectible.