Best thing about Bitcoin is that you don't have to park it in an offshore account. It's offshore by design.
Discussion
Unless it's being held via an exchange or other custodian, then I'd definitely consider it "on-shore".
You'r keys are always technically "local" until proven the opposite, so definitely not sure from a legal point of view. Nonetheless, practically it is, you joust need to defend yourself from eventual legal annoyance.