Hi OP, I am not an expert but think I am fairly knowledgable, I am sure someone will correct me if I am wrong. You would probably get better answers if you were clear on
what you want to do
why you want to do it
sate what period the pay is (weekly/monthly etc)
how many hrs are worked in the pay period
Salary (asuming salaried)
An employers contribution can technically pay any amount up to 60k per year as employer contributions, so 5k per month, this would use the full annual allowance so no employee contributions. However HMRC require the total employee package salary and employer contributions to pension, company car etc be reasonable for the specific job role. So an employer wouldn't be able to pay min wage (23k) + 60k to a pension for a role that usually commands a salary of 30k.
Usually salary sacrifice will show gross pay, then deduct the proportion that is sacrificed by the employee, before tax and NI are calculated.
On the payslip above it seems like your contract must have been adjusted to show a lower salary and specify a higher employer pension contribution. Whilst this can be the arrangement I dont think I am informed enough to outline all the positives and negatives of that arrangement.
Assuming the payslip you provided is monthly for a salaried employee contracted for 37.5hr wk, I think the actual gross pay of 1950 is already below min wage which is not allowed. Gross pay for min wage, before tax and ni deductions for someone aged 21+ should be £2,065.38.
If over 21 and salaried, to work out the lowest gross pay
Take the number of hours worked in a pay period
multiply by the minimum wage of £12.71
anything above that number could be sacrificed by the employee.