If you wait too long before reporting it to eBay, you will not be entitled to have your final value fees refunded. You should open a "disputed item" claim right away. EBay will then contact the buyer and tell him/her that the transaction has been reported for non-payment, and reminding the buyer to follow through. You are entitled to seek a refund of your final value fees only after 7 days have passed from the opening of the dispute. If you never open the dispute, you never qualify for the refund.