When Sarbanes-Oxley was passed in 2002, many companies were forced to take an in-depth look at internal Accounts Payable controls. Implementing internal controls takes time, but may prove to be a very cost-effective measure if any fraud or leakages are found. Here are a few approaches you can try to tighten up your A/P audit. They require some degree of data mining and programming capability but are fairly straightforward to implement.

1) Duplicate Payments

Duplicate payments in most cases may not be fraud-related, but continue to be a significant A/P leakage that is both preventable and recoverable. Mark Van Holsbeck, Director of Enterprise Network Security for Avery-Dennison, estimates that corporations make duplicate payments at the rate of 2%. Two percent may not sound like much, but if your company’s A/P invoices total $75 million, duplicate payments may account for $1.5 million. Take a look at the statistics:

Medicare - The Dept of Health & Human Services’ Inspector General estimated that Medicare made $89 million of duplicate payments in 1998.

Cingular - We have once again discovered that payments made online as an Electronic funds payment for TDMA accounts, have been deducted twice from the customer's checking account.

Medicaid - We identified at least $9.7 million in such duplicate payments during our two-year audit period, and estimated that as much as $31.1 million in additional duplicate payments may have been made.”

In a rush to find the overpayments, many companies have emerged: A/P Recap, Automated Auditors, AP Recovery, ACL, Cost Recovery Solutions, and more. That these companies are thriving is a testament to the fact that duplicate payments still occur at an alarming rate.

Many software packages have some controls over duplicate invoices but it usually takes some in-depth querying to find them all. For example, many accounting packages do a duplicate invoice check and prevent you from keying in a duplicate invoice number for the same vendor. But just add an “A” to the invoice number or change a penny and you are on your way to a duplicate payment. Another common mistake is found in vendor files; duplicate vendor numbers for the same vendor is the number one cause of duplicate payments.

A programmer in your IT department will be able to help you with the SQL code for these joins. The SQL code will look something like this to create the first report “EEEE”:

CREATE TABLE DUPES_EEEE AS

SELECT A.*

FROM INVOICES A, INVOICES B

WHERE A.VENDORID=B.VENDORID AND

A.INVOICENUM=B.INVOICENUM AND
A.INVOICEDATE=B.INVOICEDATE AND
A.INVOICEAMT=B.INVOICEAMT AND
A.ID B.ID

The ID field should be a unique record identifier to distinguish one record from another. In Microsoft Access, these fields are usually created by using the data type “AutoNumber”. In open code, a field such as this can be easily created using a counter and incrementing it by 1 for every record (COUNTER = COUNTER + 1).

2) Implement some fuzzy-matching

Implementing “similar” fuzzy-matching instead of exact matching is what makes this approach more accurate and powerful than many. We define “similar” to mean the following:

Invoice numbers are considered similar if they are exact after stripping out any

zeros and any alphabetic characters as well as punctuation characters.

Invoice dates are considered similar if the difference between the dates is less than a designated amount such as 7 days. For example, if you entered "7" days for the date tolerance, then all invoices with a date different of 7 or less would be considered similar. We generally set the date tolerance to 21 days to catch duplicate payments made 3 weeks apart; this often eliminates catching legitimate rent payments.

Amounts are considered similar if they meet one of three criteria:

1. the amounts are 5% +/- the other amount

2. one amount is exactly twice as much as the other, i.e. $220.15 and $440.30

3. the amounts start with the same first 4 digits, i.e. $123.45 and $1,234.55

Try using similar matching on the invoice number, date, and amount fields when you conduct your next duplicate payment audit – your reports will be shorter and more accurate!

2) Benford’s Law

What is it?

Benford's Law (which was first mentioned in 1881 by the astronomer Simon Newcomb) states that if we randomly select a number from a table of physical constants or statistical data, the probability that the first digit will be a "1" is about 0.301, rather than 0.1 as we might expect if all digits were equally likely. In general, the "law" says that the probability of the first digit being a "d" is

Where ln refers to the natural log (base e). This numerical phenomenon was published by Newcomb in a paper entitled "Note on the Frequency of Use of the Different Digits in Natural Numbers", which appeared in The American Journal of Mathematics (1881) 4, 39-40. It was re-discovered by Benford in 1938, and he published an article called "The Law of Anomalous Numbers" in Proc. Amer. Phil. Soc 78, pp 551-72. [1]

You can actually re-create this function in Excel quite easily. In one column, type 1, 2, 3, through 9, making 9 rows in cells A1 through A9. In the second column, cell B1, type the function “=ln(1 + 1/A1) / ln(10)” and copy this function for cells B2 through B9 and it will create the probabilities.

How is it used to identify fraud?

If we know the normal frequency of digits, then we can identify digit frequencies that violate that normal behavior. For example, Benford concluded that, out of a group of numbers, the first digit will be “1” about 30% of the time. Similarly, using the same function, we can expect the first digit to be “8” about 5.1% of the time. Expected frequencies for each first-digit of the invoice amount are shown in the graph below:

If we review Accounts Payable invoices and determine the first digit of the invoices is “8” 50% of the time, then we may have either many legitimate payments that start with “8”; or we may have fictitious invoice amounts. Fraudsters will often create an amount that starts with a higher number, like 8 or 9, not knowing that auditors are now equipped to identify these abnormal payments.

3) Rounded-Amount Invoices

People who commit fraud often create invoices with rounded amounts, which are invoices without pennies. Yes, you would think the fraudster would have “cents” enough to do otherwise. An easy way to identify rounded-amount invoices is to use the MOD function in Excel. Suppose your invoice amount is $150.17; then MOD(150.17,1) gives you the remainder of dividing 150.17 by 1, which is .17. So, using the MOD function with a divisor of 1 on a no-pennies amount would leave us a remainder of 0. Additionally, try to rank your vendors by those with a high percentage of rounded-amount invoices. To do this, just calculate each vendors’ number of rounded-amount invoices and divide it by the total number of invoices for that vendor, obtaining the percentage. Then rank by descending percentage to review the most suspicious vendors first.