Still gathering requirements...

Originally Posted by
malvolio
Hang on a minute.
This all depends on who made the original outside IR35 determination, how good it is (e.g. if a professional reviewer is happy then everyone should be) and if the now inside determination has been challenged and verified.
We still have a part to play in these scenarios: just because companies can't be arsed to read the legislation properly doesn't mean we have to accept what we're being told. You can always fight back - in fact the more that do, the better. Section 10 states quite clearly that you must have a specific determination.
It will be the contractor who initially determined it to be outside of IR35 (albeit maybe with the advice of someone else, it is the contractor who owns the risk).
If the contractor then signs an identical contract for the same client that is inside IR35, they are admitting a fault in their initial assessment of the contract (Outside) and endorsing the clients assessment (Inside). HMRC are then entitled to back tax it appropriately.
By not signing the new contract you are standing by your initial assessment. That is your defence.