Any ideas here? I'm trying to create a formula that sets a date, from another date, based on a picklist value(annual, quarterly, etc.) However, when I try and save the formula, I'm told I have 16,000+ characters and the limit is 5000, when in fact the formula is 1313 characters.

Is this a "fake" error and I should be doing this type of calculation another way? Is it a bug? Thanks

IF( ISPICKVAL( Billed__c , "Custom") , Custom_Renewal_Date__c ,
IF( ISPICKVAL( Billed__c , "Quarterly") , 
CASE(MONTH(Close_Date__c),
1,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , IF(DAY(Close_Date__c)>30,30,DAY(Close_Date__c)) ),
2,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , IF(DAY(Close_Date__c)>27,31,DAY(Close_Date__c)) ),
3,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , IF(DAY(Close_Date__c)>30,30,DAY(Close_Date__c)) ),
4,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , IF(DAY(Close_Date__c)=30,31,DAY(Close_Date__c)) ),
5,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , DAY(Close_Date__c) ),
6,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , DAY(Close_Date__c) ),
7,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , DAY(Close_Date__c) ),
8,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , IF(DAY(Close_Date__c)>30,30,DAY(Close_Date__c)) ),
9,DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , IF(DAY(Close_Date__c)=30,31,DAY(Close_Date__c)) ),
10, DATE( YEAR( Close_Date__c ) +1, 1 , DAY(Close_Date__c) ),
11, DATE( YEAR( Close_Date__c ) +1, 2 , IF(DAY(Close_Date__c)>28,28,DAY(Close_Date__c)) ),
12, DATE( YEAR( Close_Date__c ) +1, 3 , DAY(Close_Date__c) ),
DATE( YEAR( Close_Date__c ) , MONTH(Close_Date__c)+3 , DAY(Close_Date__c) )
) ,
NULL))