Question mostly covered in the title and summary.
Sorting out historical issues for a client that are partly their fault and partly down to a bad adviser. Company was struck off by Companies House for failure to file a confirmation statement. Administrative restoration subsequently applied for prior to them coming to us.
I have a copy of an HMRC letter pre-dating the strike-off showing a UTR. Attempting to submit corporation tax returns states the UTR fails checks. Attempting to register as agent using that UTR does not work, even trying former registered office postcodes.
Does striking off and restoration change the UTR? If so, how would we go about getting the new UTR, as HMRC appear not to be sending normal CT letters to the client?