The employer and employee can file a joint request for the 30% ruling.
When the 30% ruling is granted, the incoming employee will exchange a maximum of 30% of his/her original wage for a tax-free allowance. The originally agreed wage will be reduced with the tax-free allowance of maximum 30%. The employer and employee must agree with this reduction (according to labor law) in a contract. This is possible, for example, in a supplement to the employment contract.
Click on the following link for a template of an addendum for the 30% ruling: