Ya

more than one month past due is probably most likely or these amounts due would probably not be specifically categorised. However, outstanding is a little more vague...keeping Henry's comments in mind and the slight ambiguity of the original phrasing.

and I would use "outstanding balance" instead of "debtor balance" to read ..verification of outstanding balances overdue by more than 30 days"

In accounting, delinquent or past due accounts are aged in a process called accounts receivable aging ("antigüedad de saldos" in the Spanish of Mexico). Consequently, the accountant makes a special annotation indicating the "age" of the delinquent account when it is 30 days old, 60 days old, 90 days old, etc. if the account goes beyond 120 days old, then things get serious and an allowance is created for that aged or old account. The worst case scenario is when the account is finally written off as uncollectible and charged against the previously created allowance. This is very strict "accounting" terminology.
Hope this helps.
18 years of translating for Mexico City based member firms of international public accounting firms (PwC, Grant Thornton, AGN, RSM, Instituto Mexicano de Contadores Públicos, A.C., etc.)

--------------------------------------------------
Note added at 2 hrs (2007-03-05 17:07:21 GMT)
--------------------------------------------------

Barron's Dictionary of Finance and Investment Terms provides ttheeh following information:
AGING SCHEDULE: A classification of Trade Accounts Receivable by date of sale. Usually prepared by the company's auditor, the "aging" as the schedule is called, is a vital tool in analyzing the quality of a company's receivable investment. It is frequently required by grantors of credit.
The schedule is most often seen as: (1) a list of the amount of the receivables by the month in which they were created; (2) a list of receivables by maturity, classified as current or as being in various stages of delinquency. The following is a typical aging schedule:

Current (under 30 days)
1-30 days old
31-60 days old
61-90 days old
Over 90 days old

The aging schedule reveals patterns of delinquency and shows where collection efforts should be concentrated. It helps in evaluating the adequacy of the allowance for BAD DEBTS, since the longer accounts stretch out the more likely they are to become uncollectible.

--------------------------------------------------
Note added at 14 hrs (2007-03-06 04:46:22 GMT)
--------------------------------------------------

The following excerpt is transcribed verbatim from the following book: Financial Accounting - W.B. Meigs, C.E. Johnson, A.N. Mosich
Pages 297-298
Aging the accounts receivable.
A past-due account is always viewed with some suspicion. The fact that an account is past due suggests that the customer is either unable or unwilling to pay. The analysis of accounts by age is known as aging the accountsm, as illustrated by the schedule given on page 298.
This analysis of accounts receivble gives maangement a useful picture of the status of collections and the probabilities of credit losses. Almost half of the total accounts receivable are past due. the question "How long past due?" is pertinent, and is answered by the bottom line of the aging analysis. About 29% of the total receivables are past due from 1 to 30 days; another12% are past due from 31 to 60 days; about 3% are past due from 61 to 90 days; and 5% of the total receivables consist of accounts past due more than three months. If an analysis of this type is prepared at the end of each month, management will be continuously informed of the trend of collections and can take appropriate actions to ease or tighten credit policy. Moreover, a yardstick is available to measure the effectiveness of the persons responsible for collection activities.