Setting up ACA hours reasons Select ACA. You can also create a measurement period from the Measurement PeriodsACA hours reasons are used only for informational purposes for ACA hours. ACA hours can be created with up to two reasons. tab of a resource in Maintenance > By Resources. In the Setup pane, click Hours Reason. Click Create. Specify the Reason and Description. In the Active field, select Yes or No. Click Save.