We have an employee newly-enrolled in the pension scheme. I ran the monthly payroll and updated it.

I realised I'd forgotten to send the payslips to HR so I rolled the payroll back to before the update was done.

Now the pension contribution amounts, both ee and er, are completely different. I can see no reason for this as nothing was changed at all, simply rolled back. 

I'm going to have to go with the new figures now but I'd like to know why this has happened as I now need to refund the employee the difference and adjust the FPS with no idea of why.

Has anyone seen anything similar?