Appendix 1: Old Error or Mistake Relief: PAYE & VAT Settlements
From 1 April 2010, it is not possible to make a claim for the old error or mistake relief for any period. The relief is replaced by overpayment relief, see SACM12000+. You will only need the guidance in SACM Appendix 1 if you are dealing with a claim made before 1 April 2010.
See BIM47090 where relief in respect of an error or mistake in a return is claimed in respect of further tax due under PAYE or ICTA88/S559 (typically as a result of an Employer Compliance settlement) and see BIM31615 where error or mistake relief is claimed in respect of a VAT settlement.