Can the 30% ruling be granted retro active?
If the application is filed within 4 months after the start date of the employment contract the 30% ruling can be issued with retro active effect till the start date of the contract the moment it is granted.
If the application is made later then 4 months after the start date of the contract then the 30% ruling can only be granted from the first of the month after the month in which the application was made.
It is therefore important that the application is filed as soon as possible to prevent that the 30% ruling is granted from a later date leading to loss of the benefit. If not all required documents are available but the employee already has a BSN then a pro forma application can be filed to secure a timely application. This pro forma application can be supplemented at a later moment.
Expatax can assist with the application: https://expatax.nl/individual-expats/30-percent-ruling/