EIM15424 | Non-approved schemes: receipts excluded from charge: prior employee contributions
From HM Revenue & Customs · Employment Income Manual
A lump sum otherwise chargeable under Section 394 ITEPA 2003 (see EIM15401) is not chargeable, or only partly chargeable, if it is attributable wholly, or partly, to the employee’s own contributions to the scheme (see EIM15414 and example EIM15438).