PSA5060 | Irregularities: Ineligible items included in a settlement
From HM Revenue & Customs · PAYE Settlement Agreements
Where you identify that an employer has offered to settle the tax/NICs liability on items that are neither covered by the PSA nor eligible for inclusion in a PSA
tell the employer how the payments should be dealt with, and
monitor future proposals by the employer to include such items in a PSA.