Define relationships between conditions
Identify independent mechanisms and those using an earlier result. A percentage list alone does not explain their combination.
Each condition needs a base, period and eligible transactions. Agreed order is insufficient if inputs are interpreted differently.
Test a normal case and threshold boundaries
A short example should trace stages to the final amount. Check an exact boundary and an adjustment changing the attained level too.
No universal sequence suits every agreement. The rule must follow confirmed terms rather than spreadsheet defaults or convenient configuration.
Preserve reproducibility
Reports should expose stages and bases, not just a total. Differences can then be explained without rebuilding everything in another file.
For accounting and analytics, reproducibility between people and periods matters. Trade Marketing can combine complex terms, but relationships and applicable versions need definition first. A technically correct calculation should implement the actual customer agreement rather than another interpretation using the same rates. Keep the test outcome with the rule so later changes can be checked against a known basis.