Under auto enrolment rules the employee has a minimum contribution to make but this cannot be under salary sacrifice if this means the EE fall under the NMW.  https://www.gov.uk/guidance/salary-sacrifice-and-the-effects-on-paye. . The 8% total minimum is required under AE, but if the Employees pension is not Salary Sacrifice then this can be applied after the NMW calculation

Thanks Steven. In this situation the pension is salary sacrifice. I have left the 3% employer payment, but reduced the employee contribution to zero.

If you reduce the EE pension value you have now not got the required minimum 8% in the AE pension contributions, and this will need to be reviewed.

The guidance states a salary sacrifice cannot drop below the NMW but does not allow for pension minimum contributions to be avoided. in this Case there would be an expectation that if the Employee is not paying then the employer would be topping up to 8%..