Employees going abroad to work (temporarily) have special expenses, i.e., expenses they would not have if they worked and lived in their own country. Hirers frequently provide things like:
Cost Of Living Allowance (COLA)
House-hunting / acquaintance trip expenses
Double housing costs – maintaining a home in their country
Extra housing costs
Travel for home leave
Cost of visas, permits, host country income tax return
Lessons to learn Dutch!
You as the employer can decide to reimburse other expenses too, such as housing or health insurance. But these are considered taxable wages. An important benefit!  International school fees are a big issue for global talent with children, and they can be reimbursed tax free on top of the 30% ruling.