I've transferred two of my P100D leases now.
The new lease applicant assumes all liability after the assumption is complete. Once a lease has been transferred once, it cannot be transferred again. Must have at least 12 or more payments remaining on the term to be eligible for a transfer.
It requires a credit application through Tesla Finance. It's an incredibly slow process and expect it to take up to 6 weeks from the day you email them to begin the application process to finally handing over the car. It is obvious that team do not prioritize lease transfers.
Further, they will give you a lot of misinformation about how the transfer works (it's very different in the US vs Canada, and they will just tell you how the process works in the US). Once the transfer has been approved and you receive a firm transfer date, you should reach out proactively to your local delivery centre who can guide you through the remaining steps. Ignore what the team in Utah tells you on the phone (such as 'waiting for a DMV form through the mail').
$150+tax application fee (nonrefundable whether approved or denied)
$500+tax transfer fee if approved and you proceed with the transfer
These fees are debited directly from the new applicant's bank account (part of the credit check includes filling out an ACH form).