WHAT IS THE M FORM?
The M form combines a foreign period with a resident period. The reason for this questionnaire is because the Dutch tax authorities have no previous information about you, which they are enquiring through this M form. The M form can’t be filed electronically but must be filed on paper.
Experience shows that most expats that file the M form, get a tax refund due to the high amount of tax that they have paid that year, while not having lived a full year in the Netherlands. In short, they have paid too much tax that year and receive a refund.