Here's one way of doing it:
1. Create a new query [QryExistingCustomers] that shows customers who have projects before March 1 of this year.
Eg:
Code:
Select Distinct CustomerName
From TableName
Where ProjectDate < #3/01/2011#
2. Create another new query that uses the above [QryExistingCustomers] and whatever the data source os for your report [is it a table or a query?].
In Design View:
Select the Table/Query that is the data source for your report.
Select [QryExistingCustomers] that you just created.
Join CustomerName between the two.
Right-click the line joining the two sources.
Click Join Properties.
Select 2 to make sure you get all records from your report data source and matching rows from [QryExistingCustomers],
Select all your fields from your existing report data source.
Select CustomerName from [QryExistingCustomers].
Where it says 'CustomerName' - type this:
NewCustomer: IIF([QryExistingCustomers].[CustomerName] Is Null, "New Customer", "")
Run your query.
Wherever there was no project for a customer before March 1, 2011 - it will now say "New Customer" - otherwise - nothing will show.
Hope this helps!