It is necessary to set validity for a cost item.
If you create a new cost item, the cost item is set to never valid by default. This prevents you from accidentally putting an incorrect costs item live.
You can choose the following options:
Always valid.
Never valid.
Valid for a specific period; then select the period group in which the expense item should apply. You can set up the period groups in your administration settings.
In a period group, a cost item is valid if the arrival date falls within the period. For example, if you want to make a cost for an Easter dinner and you want a guest who arrives well before Easter to be able to add this cost, make sure that you set the period group so that this guest can also add this cost.
A cost item cannot be valid on a single day. Do you want to offer breakfast on Sundays? Set up a period group for every weekend so that your guests who stay during the week are not offered this extra.