Learn how to calculate the average days sales in accounts receivable and tips for interpreting the results. Average days delinquent (ADD) is a metric that lets companies know the average number of days that late payments take to get collected.Accounts receivable (AR) is an accounting term for money owed to a business for goods or services that it has delivered but not been paid for yet. Then, you take out your gross sales from your accounts receivable to report it to the next month's accounts receivable. Days in AR = 61 days. For information or help, call one of the numbers listed: Phoenix. Check the box on line E on page 1, fill out. Schedule ACA, and include it with your return. Acceptable figures range from as low as 30 days to as high as 70. Please fill out this field.