Our cancellation policies vary, depending on the type of reservation you've made:

Was your credit card charged for the rental at reservation time on avis.com?
If you wish to cancel before your rental pick up time, you must cancel and request a refund online. Once cancelled, we will credit you within approximately seven business days. Credits will be applied to the same card with which you prepaid. You will incur a $50 processing fee if you choose to cancel a prepaid reservation before the rental, and a $150 fee after the rental pick up time has passed. If you return the vehicle before the original return date (early return), you will not be refunded any portion of the payment.

Did you make a reservation without providing credit card information?

If you make a reservation without a credit card and you no longer need to rent, please cancel your reservation as soon as possible before your scheduled pick up time.

Did you make a reservation with a travel agent or online booking agent?
The travel agency or online booking agent 'owns' any reservation you originally made with them, so their reservation cancellation processes and policies apply.