What is the difference between bad debt and doubtful debt?
Some people will use these terms or account titles interchangeably: Bad Debt Expense, Doubtful Account Expense, Uncollectible Account Expense. The same for these terms or account titles: Allowance for Bad Debts, Allowance for Doubtful Accounts, Allowance for Uncollectible Accounts.
The three Expense account titles listed above are income statement accounts and will have the usual debit balance. These expense accounts report how much bad debt expense was incurred during the period shown in the heading of the income statement.
To gain more insight on this topic go to AccountingCoach.com's explanation of Adjusting Entries, Part 1.