Unlike most top-level domains (TLDs), you can't just let your .AT domain expire if you no longer want it.

Instead, you must explicitly cancel your .AT domain by submitting a completed .AT Cancellation Form to us at least 5 days before the domain expires. If the form is not sent by then and you do not renew the domain with us, Nic.AT, the .AT central registry, will attempt to collect the renewal fees from you directly. At this time, if you do not want to keep the domain, you may be able to cancel it directly with Nic.AT.

Want to keep your .AT domain? Make sure you know when to renew your .AT domain, so you don't lose it!