ESM0111 | Procedural aspects of status cases: binding nature of opinions in writing
From HM Revenue & Customs · Employment Status Manual
People who ask for an opinion on status are entitled to an answer they can rely on.
You should, therefore, regard any previous opinion given in writing as binding except where it can be shown that:
the information provided was misleading and/or incorrect
or
the facts have changed materially since any previous opinion was given.
Where an earlier opinion was technically incorrect, we will normally be bound by it for the past. We would, however, seek to alter it for the future.
We are not bound on the status of an individual simply on the basis that they have, for example:
registered for VAT
made returns assuming self-employment
applied and been accepted to pay self-employed NICs, or
received a decision from an Employment Tribunal.