Late payment penalties yes, loss of earnings? 
If you go after them for late payment penalties, even if you never get it, it will be a nice thing to show HMRC if they ever come around claiming you are a disguised employee. It won't win your case if you really are inside IR35, but if you are borderline it could help.

If you go after them for late payment penalties, even if you never get it, it will be a nice thing to show HMRC if they ever come around claiming you are a disguised employee. It won't win your case if you really are inside IR35, but if you are borderline it could help.

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