Base month is the index month the LPS regulation is calculated from, typically the latest known index when the tender was submitted or the contract signed. The reduction factor reduces how much of the index change is included. The field has a default value, so if you are to have full index regulation, set it to 0.
How to set up LPS on the billing schedule
Update the billing schedule first. LPS is calculated from the amounts in the schedule.
Go to Billing Schedule Client, hover over the schedule name and click the pencil.
Turn on Index regulation.
Select an index from the list, for example an index from Statistics Norway (SSB), or create a new one.
Set the base month.
Check the reduction factor. Set it to 0 for full index.
Save.
Check the result
You see the result in the LPS view above the table, next to Revenue and Withheld.
Common mistakes
The default value in reduction factor is left unchanged even though you are to have full index. LPS then becomes too low.
Two indices on the same schedule. Select only one index per schedule, otherwise the calculation will be wrong.
Base month is confused with the contract period. The contract period is set in Contract details and is something else.