When do I need to file an M-form
In 2 cases you are obliged to file an M-form. 1) Upon invitation from the Dutch tax authorities. 2) You need to pay income tax and are aware of that fact.
How do I file an M-form and deadlines to be considered
You can file an M-form online yourself through the website of the Dutch tax authorities. This will require a DigiD. Or request a paper form by phone +31(0)55 5385 385. There is no download available on the website of the Dutch tax authorities.
Normally the 1st of July is the deadline for filing. As an individual taxpayer you can get an extension yourself for another 3 months. Most tax advisors (me included) can obtain an extension of a full year.
Do I need a tax advisor to handle my M-form
In all honesty this depends entirely on your situation. Some cases are straightforward and require no expert tax knowledge. But is this your situation? As a non-professional you are never sure. In other cases, double taxation tax treaties, allocation of tax-deductible items between fiscal partners, social security issues, fiscal residency, complicated tax law and court rulings come into play.
And there is the language barrier to consider while filing yourself. Both the online option and the paper form are strictly in the Dutch language. In most cases the fee you pay your tax advisor gets you the most profitable tax return and buys you at least some peace of mind.
Filing an M-form is often profitable
The amount of wage tax withheld by your employer is based upon a reporting period of 12 months. The year upon entering or leaving the Netherlands consists of fewer reporting months. Resulting in too much wage tax being deducted. You can get a tax refund if you file an M-form.
Make sure the Dutch tax authorities know how to reach you
Upon leaving the Netherlands the Dutch tax authorities will send the M-form and all other correspondence to your forwarding address. Not receiving their letters abroad can result in costs and fines.
For example: Not receiving the M-form and subsequent reminders to file your income tax return will result in an estimated tax assessment. The Belastingdienst likes to exaggerate the amount of income tax due in these cases to spark a sense of urgency.
Therefore, it is wise to get a Digid and activate your government e-mailbox at MijnOverheid which will enable you to receive all communication digitally. Even after leaving the country.
Qualifying non-resident taxpayer
In some circumstances it is possible to be considered a resident taxpayer for the entire year. Also, for the period you spent outside of the Netherlands. This means you are entitled to the same Dutch tax facilities as residential taxpayers. For example, making negative expenses (mortgage interest) from your home abroad deductible.
To qualify you need to live in an EU country, Liechtenstein, Norway, Iceland, Switzerland or one of the BES islands. At least 90% of your worldwide income needs to be subject to Dutch income tax. And you need an income statement from the tax authorities in the country of residence. Obtaining one can sometimes be a challenge.
Keeping up with tax developments is vital. If you don't when are you going to find out? Exactly when you're ready to file your taxes from the previous year. And by then it will be too late to correct any fiscal mishaps.