What other allowances, in addition to doubtful accounts, might be necessary to value accounts receivable correctly?

Question:

What other allowances, in addition to doubtful accounts, might be necessary to value correctly?

Accounts Receivable
Accounts receivables are debts owed to your company, usually from sales on credit. Accounts receivable is business asset, the sum of the money owed to you by customers who haven’t paid.The standard procedure in business-to-business sales is that...