SolvedETASSUM36160 | Schedule 3 SAYE option schemes: Exchange of options: Income tax consequences
From HM Revenue & Customs · Employee Tax Advantaged Share Scheme User Manual
No income tax charge under Section 476 arises on the release of an option (tax advantaged or non-tax advantaged) in exchange for another option (Section 483 ITEPA).
Paragraph 39(5) provides that for the purposes of the Schedule 3 SAYE code the new options are regarded as having been granted when the old options were granted.