The period in Setup and Operation controls which months costs can be accrued to, and shouldn't be limited to the construction period itself. Start the period in the month the first costs actually arrive, and end it a couple of months after planned completion, so final invoices and other late costs are included.
How to set the period
Go to Setup and Operation.
Open the date picker and set From date and To date.
Check that the start month covers costs before construction starts, for example wages in the start-up phase.
Set the end month a couple of months after planned handover.
Then accrue each expense item across the months.
Why does this matter?
Starting too late: Costs that arrive before the period starts fall outside the distribution.
Ending too early: Final invoices and late costs often arrive after the building has been handed over. If the period runs a little longer, you can close the project properly.
Good to know
The period on an expense item defaults to the project period, but you can change the dates per expense item. The project period is set under Contract details on the project.