This is probably a basic level question, but...
My subbie client has had an enquiry into his return, with the revenue-bot claiming that the CIS statements are invalid because said client was not registered for CIS (an omission that occurred before we were acting and which will now be corrected). Thus it is asserted that the deductions claimed against his tax liability are unacceptable he is now being asked to cough up tax to the same value.
Now I'm 99% sure that if the deductions were being made incorrectly (in this case, at 20% instead of the unregistered 30%) then that is the contractor’s problem, not my clients (the same principle as PAYE). However, before I send off the customary ‘sierra-oscar’ response to HMRC could anyone please confirm/correct my understanding - references to legislation/regulations would be ideal.
(Apologies if it's been covered recently elsewhere around here.)