This is the ratio that expresses the percent of debts (accounts receivable) that are not likely to be collected since they are overdue (or close to defaulting) to the total amount of debt.

According to (Spanish) legislation, nonperforming loans are more than 90 days (or three months) past due; along with those accounts, paid or not, over which there exists some reasonable doubt as to whether the will be collected in full on time and in the that was contractually stipulated.

These norms are dictated by the bank of Spain. The term dubious client has been included in the Spanish Accounting Rules of 2007 (Spain), which are the same as the International Accounting Board´s rules, specifically in the way it is accounted for and evaluated in rule #8.