You can set up cancellation reasons with rules that automatically decide whether to apply a cancellation fee for a canceled appointment or mark it as "Do not invoice".

Go to Settings, Cancellation reasons and add a new reason or edit an existing one.

For example, you could set up a rule such as:

If:

Cancellation notice period is less than 2 days

Then:

Apply cancellation fee (percentage of the total appointment) i.e. 100% of the total appointment fee

Else if:

Canceled outside of the notice period (More than 2 days notice is provided) then mark the appointment as "Do not invoice" so that it does not count as an uninvoiced billable activity.

If the appointment is at 10 AM, Wed 25 Jan 2023, and canceled at 9 AM, then the cancellation rules would apply and when invoiced, the appointment total fee would apply.

If a cancellation fee of less than 100% is used for a cancellation reason, such as 50%, then when invoicing, the cancellation rate will be displayed on the invoice creation page for reference.