Hi

To solve your problem without a sample de-sensitised model is fairly difficult but maybe some advice might help.

To build a model to determine the calculations needed I would draw a flowchart of all the decision points and the decisions to be made. This will provide a base to build a model spreadsheet using formulae to determine the cashflows.

If you are familiar with flowcharting this will help in solving the issue if not then maybe a colleague in your computer department can or maybe an answer will pop up here.

I had a question though What is deduction capacity. Is it the difference between the threshold 3 Mio and interest paid/deducted?

I can give a go over the next week if no other responses are posted.

Cheers