Tesla is allowing current Tesla owners to transfer their self-driving package to a new vehicle, though, as you may expect, that ability comes with a few caveats.

During an earnings call on Wednesday, CEO Elon Musk said the company would offer “one-time amnesty” to vehicle owners who wanted to transfer the feature, although he didn’t prove any details on how the swap could happen. Tesla owner Keith Dahlenburg, however, posted more information on Twitter.

As The Verge reports, Tesla requires anyone who wants to take advantage of the deal to buy a new Tesla and take delivery of it before Sept. 30, 2023, so you don’t have a ton of time.

To transfer full self-driving (FSD) capabilities, you’ll need to forfeit the ability on your current Tesla vehicle. The software can be removed as early as one week before the scheduled delivery of your new Tesla, so you may be without it for a bit while you’re waiting.

Tesla notes that the FSD ability can only be transferred once, and cannot be transferred to another person or vehicle, even if the vehicle is privately sold.

That forfeiture of the self-driving ability also isn’t reversible, so if you ask to have it transferred and then decide you don’t want that new Tesla after all, you’ll also lose self-driving in the process. And you have to decide before you get that new Tesla, not after. Tesla won’t let you apply the offer retroactively after the vehicle has been delivered.

The ability to transfer FSD capabilities is new for Tesla. The self-driving feature is typically sold as a permanent one, and typically is not transferrable to a future vehicle owner nor by the current one to a new vehicle. The software runs $15,000, so many Tesla owners have complained that it’s a pricey thing to leave behind when upgrading vehicles.