As of my last knowledge update in September 2021, Spirit Airlines cancellation policy is subject to change, and I recommend verifying the latest policy on the official Spirit Airlines website or contacting their customer support for the most up-to-date information. However, here is a general overview of their cancellation policy based on historical information:

1. 24-Hour Grace Period: Spirit Airlines typically offers a 24-hour grace period for cancellations without incurring any fees, provided the booking was made at least seven days before the departure date.

2. Standard Cancellation Fees: After the grace period, cancellations or changes to flights may incur fees, which can vary based on factors such as the fare type and the time of Spirit Airlines cancellation.

3. Flight Flex: Spirit Airlines offers a Flight Flex option during booking, allowing passengers to make changes or cancel their flights without additional fees (fare difference may apply).

4. Non-Refundable Tickets: Most of Spirit's fares are non-refundable, meaning that if you cancel, you might receive a credit for future travel on Spirit Airlines (subject to applicable fees).

5. Refundable Tickets: Some premium fare types may be refundable, allowing passengers to receive a full refund in the original form of payment.

6. Involuntary Cancellations: In certain situations where Spirit Airlines cancels a flight, passengers may be eligible for compensation or a refund.

Remember, policies can change, and it's crucial to check the specific terms and conditions related to your booking. Always review the cancellation policy before purchasing tickets to understand your options in case of any changes to your travel plans.