Answers
How do we switch accountants?, Appoint the new firm, which writes to the old one for professional clearance and handover information, then authorise them as your agent with HMRC.
Do we have to wait until the year end?, No. Switching mid-year is normal. The main point to agree in writing is which firm completes the current year end.
Can the old accountant refuse to hand over records?, Your own books and records are yours. A firm may exercise a lien over its own working papers where fees are unpaid, so settle any outstanding invoice first.
Will HMRC need to know?, Yes. New agent authorisation is set up through HMRC's agent services, and the previous authorisation is removed.
Is there a cost to switching?, Usually none for the handover itself, though catch-up or clean-up work identified during the transfer is quoted separately.