At January 1, 2017, the credit balance of Indigo Corporation's Allowance for Doubtful Accounts was $409,000. During 2017, the bad debt expense entry was based on a percentage of net credit sales. Net sales for 2017 were $80 million, of which 90% were on account. Based on the information available at the time, the 2017 bad debt expense was estimated to be 0.75% of net credit sales. During 2017, uncollectible receivables amounting to $492,000 were written off against the allowance for doubtful accounts. The company has estimated that at December 31, 2017, based on a review of the aged accounts receivable, the allowance for doubtful accounts would be properly measured at $522,000. (a1) Calculate the bad debt expense accrual Bad debt expense accrual