Hi annette-king,
Thanks for joining us here on the Community :waving_hand:
If you are using the Standard Payroll, you can do this by going to the Cog Wheel > Account & Settings > Payroll > Pension pay types > Toggle on.
On the Advanced Payroll, go to Employees > Payroll Settings > Pension Settings > Select the contribution plan > Select the 'Applicable pay categories' field to add.
Get back to us below if you have any questions!