Define when prices apply
Agree the date and version assigning each transaction to its price. The current document should not automatically describe the entire period's history.
Distinguish a price change from a promotion change. A new list need not alter every previously agreed condition. Resolve uncertainties before applying a rule to the full turnover.
Retain earlier calculation bases
Data should explain how transactions were calculated before the change. Overwriting one value without history can make comparison with earlier reports impossible.
For adjustments, establish the original-event link and agreed recalculation method. The adjustment's arrival date alone does not settle every case.
Test both sides of the change
Review an earlier transaction, a later one and a boundary case. Compare price, condition base and result rather than only the total.
For a commercial manager, consistent versions reduce customer ambiguity. Trade Marketing links prices and campaigns. Timing rules determine whether settlement reflects actual agreements rather than whichever list was imported most recently, while preserving enough information for another person to repeat the calculation later.