Try this:
For
CustomerID's in Col_A on Sheet1
Delinquent list in Col_A on Sheet2

On Sheet1,
A1: (some customerID)
B1: =--ISNUMBER(MATCH(A1,Sheet2!$A$1:$A$100,0))

Adjust ranges to suit your situation.

Does that help?

***********
Regards,
Ron


"Diane Briltz" wrote:

I have customer data in an Excel spreadsheet with about 500 customers IDs in
one column and a list say 60 delinquent customer's IDs in another. I want a
simple formula to state whether a customer on the list is delinquent or not,
preferably to put a "1" in the column if the customer is on the delinquent
list, and a "0" if the customer is not.