Pension (or an annuity) in payment
The post share pension in payment is simply reduced in proportion to the percentage shared
Example
Pension in payment pre-share = £10,000 p.a.
Percentage share = 40%
Pension debit = 40% x £10,000 = £4,000 p.a.
Pension post share = £10,000 less £4,000 = £6,000 p.a.