I have a report which shows the start and end dates when users were members of an employment benefit, for some users there will be multiple entries, with the latest start date having no end date.  I need a formula which will flag those users who's latest start date is less than 52 weeks from when they previously left the scheme.  I think I'm going to have to use a sub-report but I'm a newbie to using arrays etc. Below is an example of a record in the report that meets the criteria:

User            Start Date    End Date

John Smith   22/05/11
                    22/09/10    20/04/11

Many thanks, the previous function is the one I was after.