Re NI/pensions etc:
https://www.gov.uk/employee-changes-gender
'Employees over State Pension age
You need to amend your employee’s National Insurance deductions if changing gender affects whether they should receive State Pension.
State Pension age can be between 61 and 68, depending when someone was born and if they’re male or female.
Calculate your employee’s State Pension age.
Employee qualifies for State Pension after becoming female
If your employee can claim State Pension after becoming female, update their payroll records so they stop paying National Insurance.
Employee stops qualifying for State Pension after becoming male
If your employee cannot claim State Pension any more after becoming male:
- change their National Insurance category letter from ‘C’ to ‘A’
- start deducting National Insurance from their pay
-
Employee paying reduced National Insurance contributions becomes male
Until 1977, married women could choose to pay less National Insurance. Women who opted in before the scheme ended can continue to pay at a reduced rate.
If an employee who opted in becomes male, change their National Insurance category letter from ‘B’ to ‘A’. Work out their National Insurance using the new letter on all following payments.'