To check what your cancellation policy was on cancelled bookings you need to open the confirmation email for this reservation.

Instruction: How can I check what my cancellation policy was on cancelled bookings

  1. Search your mailbox using "airbnb confirmed XXXXX" keywords where XXXXX is the guest's first name.
  2. Open the "Reservation confirmed!" email.
  3. Scroll down to Cancellations
  4. See your cancellation policy set for this reservation

Expert note: internal Airbnb documentation doesn't display cancellation policy for cancelled trips.