You can locate your Accounts Office Reference number (AORN) on the confirmation letter you receive from HMRC when you first register as an employer. The AORN contains 13 characters, and follows the format 123PA12345678.
<p>You can locate your Accounts Office Reference number (AORN) on the confirmation letter you receive from HMRC when you first register as an employer. The AORN contains 13 characters, and follows the format 123PA12345678.</p>