Q:

How do I group Accounts/Contacts by $ amount of all won opportunities this year?

My company wants to automatically group Accounts/Contacts by ranges of money spent this year. 
For example:
Top Buyer (won opportunities totaling >$25k)
Medium Buyer (won opportunities totaling $10k-25k)
Low Buyer (won opportunities totaling 

There's already a field for "Total Purchases This Year ($)". How do I get that field to then automatically update another picklist field with the Top, Medium, Low options? Is there a way to then remove the field data after no won opportunities in the past year?
For example, if someone makes a $1000 purchase, I would like a way for that contact to automatically be designated as a "Low Buyer", but to be designated null after one year of no action.

A:

You can create a Roll-Up Summary field on Account to calculate SUM of Amounts, and set a Filter Criteria for CloseDate (you can't use Relative Date Values here, so would have to setup greater than and less than of actual year start and end dates), and also for Closed Won Status.
After this you have to create a formula field like:
IF( MyYearRollUp__c > 25000,
 'Top Buyer',
 IF( MyYearRollUp__c > 10000,
  'Medium Buyer',
  'Low Buyer'
 )
)

One downside is that you have to update year start/end dates once a year, but this is not that much of work at all.

