This chapter discusses the modelling approach for both value‐in‐force (VIF) and catastrophic mortality transactions. It is pointed out that for a VIF transaction or an excess reserve transaction, a traditional actuarial projection model is used to develop projected insurance cash flows and insurance liability items such as statutory reserves and tax reserves. The outputs from the actuarial model for the baseline projections and for the sensitivity test projections are then included as input into the deal model, which then reflects all of the terms of the proposed transaction to determine the availability of cash flows to service the debt contemplated under the transaction. Both because of the limited amount of historical data available on the main risks in these transactions, and to test the potential for future experience to be different from past experience, it is important to test a wide range of sensitivities on the key underlying assumptions in the transaction.