According to their website:
What happens if I cancel?
It depends on the time you cancel:
1) Cancellation outside of the "Late Cancellation Period": Each hotel has a "Late Cancellation Period", which tells you up to which time you can cancel to avoid a late cancellation fee of one room night plus tax. For most hotels this Late Cancellation Period is 3 nights or 72 hours before arrival (cut-off time is 3:00 p.m.). Some hotels have a "Late Cancellation Period" as long as 7 days or even longer. Please check on your hotel's "How to Pay" page for details concerning cancellation time frames. As long as you cancel outside the "Late Cancellation Period" as defined by each individual hotel on the "How to Pay Page", you will not be charged one room night plus tax by the hotel. All you will be charged is a cancellation fee of $10.00 by HotelKingdom.com to compensate for the work we have done for you.
2) Cancellation within the "Late Cancellation Period": If you cancel late, in other words within the "Late Cancellation Period", there will be no charge from HotelKingdom.com; however, the hotel will charge you one room night plus tax. The reason for this charge is that the hotel had guaranteed your room or suite, and that it will be very difficult for the hotel to sell your accommodations at such short notice. the late cancellation fee of one room night plus tax will be charged by the hotel on your credit card. Sometimes hotels waive the Late Cancellation Fee, especially in case of emergency. We at HotelKingdom.com will be glad to be your advocate and help you in case of cancellation as much as we can; however, the ultimate decision at to whether or not to charge you the Late Cancellation Fee will rest with the hotel.
