Not true, my accountant has a contract where she is responsible for any mistakes or miscalculated taxes etc so she has to pay them. She does have a registered accountancy office though and insurance against this sort of thing though so the risk for her is also minimal.

That doesn't sound like an in-house accountant (i.e. an employee) but that you are engaging an external accountant to work for you - completely different commercial relationships.

And they typically have liability insurance anyway. Your contract is not worth the paper it's written on if the accountant is unlikely to be able to ever repay the loss.