You can ask HMRC Clearances Team to confirm the tax and NICs implications of a salary sacrifice arrangement once it is in place. However, this is not a requirement.
HMRC would want to see:
- evidence of the variation of terms and conditions (if there is a written contract)
- payslips before and after the variation
This can be emailed to the HMRC Clearances Team at firstname.lastname@example.org.
Or sent in the post to
HMRC Clearances Team
21 Victoria Avenue