Hey Guys I need your help once again,
Im current working on a report that requires me to implement effective dates for fees i created a report that shows fees but it changes the ones already been billed. so i need help with a formula:

Example:

Procedure code             Current Eff. Date      Current Fee            Previous Fee
Manual Therapy             3/1/2012                   $50.00                  $56.00


sorry i left out. effective date is applied to date of service.