Remember to request your refund within three months. It works as follows:
Step 1: register
Go to uitcheckgemist.nl and sign in using your OV-chipkaart number. If you have a personal OV-chipkaart, also enter your birthdate.
Step 2: enter info
The website lists all rides without a check out. Note: It may take up to 14 days before you see your missed check out refund. If after this period your trip still does not show up, you can try again after a few days.
Want to request a refund for a trip? Enter the boarding location and the destination. The balance will be dislayed immediately.
Step 3: collect
Your requested balance refund will be readied. You can reload it on your OV-chipkaart at an add value machine and then use it to travel.