If you come to work in the Netherlands, you may incur additional costs, the so-called extraterritorial costs. Your employer may grant you a free (untaxed) allowance for the extraterritorial costs you incur. Instead of reimbursing the actual extraterritorial costs, your employer may also reimburse extraterritorial costs by providing 30% of your wages, including reimbursement, tax-free. This scheme is known as the 30% ruling. For this it is not necessary to prove any expenses.
You must have permission (a ruling) from the Dutch tax authorities for the application of the regulation. You can submit a request for this together with your employer. You are eligible for this reimbursement if you meet a number of conditions.