Depending on your current situation, you may be obligated to file an income tax return with the Dutch tax authorities (Belastingdienst).
The moment that you register or deregister with your city hall in the Netherlands, you are considered, for tax purposes, a migrant. The tax return for you is then the Migration income tax return or the so- called M-form.
In the Netherlands, you are free to file your own income tax return. However, many internationals may not be excited over taking care of that 80+ page Dutch M-form on their own.
The further away from January 1 that you either arrive in or leave the country, the higher the potential of you getting a refund. Because the M-form often results in a refund, the Belastingdienst is not too keen to invite you to file - which is why it is a good idea to file this form either yourself or through a Dutch tax advisor.
The moment that your employment income is your only source of income, you will probably not be invited to file an income tax return in the Netherlands. Specifically, this means that you do not own your home and you do not have assets exceeding the 57.000 euros Box 3 threshold as of January 1, 2023.
Also, if you have a partner and your combined assets does not exceed 114.000 euros, then you also probably won't be invited to file. If you are invited, however, then you are obliged to file.
Those who have already claimed a refund, paid a preliminary assessment, claimed a tax credit (toeslagen) are obliged to file. If you do not file, the refund and the tax credit needs to be paid back. If you expect to receive more of a refund, file before April 1, 2024. This way, the belastingdienst will promise to pay the refund out to you around July 1, 2024.
The moment that you are not a Dutch resident taxpayer, you can still be a non-resident taxpayer for any property that you own in the Netherlands. This is taxed in Box 3 and it is currently not the most exciting box to be taxed in.
However, let's say for example that you had already left the Netherlands in 2022, but your employer paid out your bonus or severance payment in 2023. We assume that the employer withheld the maximum tax over that payment, as that is - from the perspective of the employer - the safest option during an audit.
This is not in your best interest as you most likely should have paid much less than that. The part that you paid too much of can then be claimed back via the annual income tax return.
In the Netherlands, you can file your own income tax return. However, depending on your tax residency status and your unique situation, the process may be time-consuming and difficult. If you are in doubt, it is best to contact a tax advisor to ensure that your taxes are filed properly and on time.