On January 1, a company's allowance for doubtful accounts had a credit balance of $21,000. During the year, it had net credit sales of $800,000 and it had $25,000 of uncollectible accounts receivable that were written off. Past experience indicates that the allowance should be 8% of the balance in receivables (percentage-of-receivables basis). If the accounts receivable balance at December 31 is $300,000, what is the bad debt expense for the year? $21,000 $28,000 $24,000 No credit adjustment needed $4,000