PAYE95011 | Reconcile individual: HMRC delay: ESC A19: employer error
From HM Revenue & Customs · PAYE Manual
When reviewing an ESC A19 claim, if you discover that the underpaid tax has occurred because of an employer error and not because of HMRC failure to make proper and timely use of information, then the employer should be pursued for payment of the tax.
Under-deductions caused by employer error commonly occur for the following reasons
Using an incorrect tax code
Failure to follow the P45 / P46 procedure
Incorrect deduction due to incorrect use of tax tables
Incorrectly considering an individuals’ tax status
Payment of gross pay without operating a code
For cases where tax is underpaid because of an employer error, refer to the Customer Operations Guidance Gateway for the employer error action guide.