Need formula that provides deferred revenue for SaS maintenance

[Esimmonds]

Hello,

Please help with my problem I am trying to create a revenue recognition schedule for SAS maintenance. It is based on invoice date/start date/recognition month and dollars. My problem is the recognition of dollars in the month it belongs (if the invoice date is after the start date then the dollars the billed month must reflect the current month dollars and the months that should have been previously recognized).

Thank you in advance for any help.