logic based calculations

logic based calculations

Hi
can anybody help me?
I need to plot of financial forecast from information in our CRM that splits a payment based on a bunch of logic statements.
As an example:
if supplier = A then split the payment into 10 parts, starting from three months after a start date.

If supplier = B split the payment into two parts, the first being 80% of the total owed, paid one month after contract starts the second been 20% one month after the contract ends.

The payment = estimated quantity used * profit margin 

This info sits in CRM and I need it to calculate which month our expected income will land.
Then it tells Books and we check the income each month to see if we have received the right amount.

We used an old Access data base to to it but not sure where a range of conditions based calculations would sit in Zoho??
CRM, or Books or is creator somewhere to build routines do do this 

thanks in advance for your help :-)

bit confused!!