I am trying to find a formula that I can use to calculate the billing
frequency as a date. I have a contract start date and a contract end date
along with our billing frequency; such as monthly, quarterly, semi-annually,
and annually. What I need is a column that will tell me the next date the
contract will bill.

for example:
Contract Start Date 1/1/2007
Contract End Date 1/1/2009
Billing frequency Monthly

I want the column to put in that this contract will bill again on 1/1/2008

thank you for any help