apple care transferable

Yes, it is transferable. You will need to call Apple; you may have to supply the serial number, your name, etc. and the buyer's name, etc. I've transferred several Applecare plans for Macs - make sure you give the buyer a proper purchase receipt which includes both your names, addresses, the exact model of the iPad and serial number as well as the Applecare plan registration number. That way, the buyer can prove that they didn't steal it.

Have a look at How to transfer coverage of an AppleCare agreement

I've tried to follow that procedure several times and Apple was not at all interested, so I finally gave up and do it my way - since they told me that the Applecare is tied to the serial number, not a person, I make sure I have a purchase/sales receipt with all the relevant information so the buyer can prove that they did not steal it.

For instance, the recent Seagate recall applies to an iMac which I sold back in March - I got an email, called Apple and was told that it wouldn't matter who would call or take the Mac in as long as the serial number matched their records. So, I sent the buyer a copy of Apple's email so he can get his hard drive replaced.