At the top it says what kind of letter it is and which year or period it covers. Those two lines decide what you have to do, and how fast.
In short
The Belastingdienst, the Dutch tax office, sends its post on paper in a blue envelope. If you choose digital post, part of it arrives in the Berichtenbox of MijnOverheid, starting with the income tax letters. As a business owner you mainly get five kinds of letters: an aangiftebrief (you must file an income tax return), a voorlopige aanslag (an estimate, payable in instalments), a definitieve aanslag (the final bill after your return), a naheffingsaanslag for VAT (a return or payment is missing) and a fine, for example € 82 for a VAT return that arrives late. If you disagree with an assessment or additional assessment, you object within six weeks of the date on the letter; you cannot object to a provisional assessment, you change it. The date on the letter sometimes lies in the future: letters are sent early, and deadlines count from that date.
The essentials
Paper or digital
On paper in a blue envelope. With digital post, part of it arrives in the Berichtenbox of MijnOverheid (with DigiD), the income tax letters first.
Objection
Within 6 weeks of the date of the assessment or additional assessment. Not against a provisional income tax assessment: you change that one.
Paying
Within the period on the assessment; for an income tax assessment usually 6 weeks from its date. If you pay later, the Belastingdienst charges collection interest.
Late VAT return
€ 82 fine if the return arrives more than 7 days after the deadline. Paid late: 3% of the amount, at least € 50, at most € 6,709.
Date in the future
Normal: letters go out before the date printed on them. Deadlines count from the date on the letter.
Example: an additional assessment because you forgot a VAT return
You forgot the VAT return for the second quarter. The Belastingdienst sends a naheffingsaanslag with an estimated amount of € 2,000. In reality you owed € 600 VAT. The amounts are made up; the steps and fines are those of the Dutch tax office.
Example: an additional assessment because you forgot a VAT return
On the naheffingsaanslag
€ 2,000 estimated VAT. An estimate: do not just pay it
Step 1
File the VAT return for the second quarter after all, in Mijn Belastingdienst Zakelijk: € 600
Step 2: pay three amounts
€ 82 fine for the late return + € 600 VAT + € 50 late payment fine (3% of € 600 is € 18, the minimum is € 50) = € 732, using the payment reference of the naheffingsaanslag
After that
A 'Mededeling Omzetbelasting' (the fine has arrived) and a 'Kennisgeving Omzetbelasting Vermindering' with the adjusted amount. If the latter does not arrive within 2 weeks of the date of the naheffingsaanslag, request a deferral of payment in writing from the Landelijk Incasso Centrum
What follows: an additional assessment after a forgotten return is an estimate, and it goes down once you file the return. The amount you really have to declare is in your bookkeeping. In booxx your VAT returns are listed per period with the amount per box, and the dashboard shows the return that is still open with its deadline and the number of days you have left.
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Blue envelope or Berichtenbox
Post from the Belastingdienst comes on paper in a blue envelope. You can also choose digital post: messages then arrive in the Berichtenbox of MijnOverheid, where you log in with DigiD. The Dutch tax office is digitising step by step and starts with the income tax letters; business post is a separate choice in Mijn Belastingdienst Zakelijk. If you do nothing, everything keeps coming on paper.
If you go digital, open the Berichtenbox regularly and switch on the e-mail notification in MijnOverheid. A letter sitting unread in the Berichtenbox counts just as much as an envelope on the doormat: the deadlines run regardless.
Which letter is which?
For income tax you get three kinds of letters that look alike. An aangiftebrief says you must file a return, and by when. A voorlopige aanslag is an estimate of what you will pay for a year, usually in monthly instalments. A definitieve aanslag is the final bill after your return; what you already paid through the provisional assessment is set off against it. For the Zvw contribution, business owners get separate assessments.
For VAT you get a naheffingsaanslag when a return or a payment is missing. After a forgotten return it shows an estimated amount, often with a fine. If you file the return after all and your real VAT is lower than the estimate, a 'Kennisgeving Omzetbelasting Vermindering' follows with the adjusted amount; if it is higher, you pay the naheffingsaanslag and a new one follows for the rest. The top of every letter states the kind of letter and the year or period; together they tell you what to do.
Deadlines: everything counts from the date on the letter
The Belastingdienst prints and sends letters before the date printed on them, so that you have them in time. A date in the future is therefore normal, in the Berichtenbox too. Deadlines count from that date: six weeks to object to an assessment or additional assessment. You pay within the period on the assessment, for an income tax assessment usually six weeks; if you pay later, the Dutch tax office charges collection interest.
A provisional assessment works differently: you pay it in one go at the latest one month after its date, or in monthly instalments until the end of the year. How that works and how to change it is in the guide to the voorlopige aanslag.
If you disagree, or cannot pay
If an assessment or additional assessment is wrong, object within six weeks: online, with a form or by letter. In a letter you put the date, your name and address, the assessment number, the reason for your objection and your signature. If you cannot substantiate your objection within six weeks, ask in your objection whether you may do so later. If you are too late, you can still request a reduction.
If you cannot pay on time, do not wait: in some cases the Belastingdienst offers a payment arrangement or a short deferral, even after the payment date has passed. If you filed a forgotten VAT return after all and the 'Kennisgeving Omzetbelasting Vermindering' has not arrived two weeks after the date of the naheffingsaanslag, request a deferral of payment in writing from the Landelijk Incasso Centrum.
Having a letter explained in your own language
In booxx you go to Reports, Letter from the Belastingdienst and take a photo of the letter, or choose a PDF; a letter with several pages you select in one go, up to six pages. After a few seconds it is explained on your screen, in the language you work in: what kind of letter it is, the amount, the date by which you have to pay or respond, the payment reference, the assessment number, the last day to object, one sentence on what to do now, and a full translation to read through.
If the letter is a VAT (additional) assessment for a period, the software puts the amount next to the return for that period that you filed through it or recorded in it as filed, and you see straight away whether it matches or by how much it differs. With a letter about income tax you get a link to your income tax reservation; a provisional assessment is an estimate, so the software does not say whether it is right. The letter is read by an AI service. In what the software stores from the letter (the explanation, the translation and the references) your citizen service number (BSN) is made unreadable. The photo itself is deleted after reading, unless you choose before uploading to keep it with your books; a kept photo stays as it is. The software does not object or respond on your behalf: for that, go to your accountant or a tax adviser.
What the software keeps track of
Most VAT letters come from a return that was forgotten or late. In booxx the dashboard shows the VAT return that is still open, with its deadline and the number of days you have left, and one click takes you to the return with the amounts per box. If an additional assessment arrives anyway, you put it next to your own figures.
For income tax, the IB & Zvw reservation screen calculates from the profit in your books roughly how much to set aside for income tax and Zvw, so that an assessment is no surprise. The Dutch words you meet in the letters are explained in the glossary of this knowledge base. The software works in English, Dutch, Polish, Hungarian and Romanian.
Updated October 2, 2026. General explanation of the Dutch rules, not tax advice — for your own situation, decide together with your accountant or the Dutch Tax Administration.
Frequently asked questions
Can I have a letter from the Dutch tax office translated?
Yes. In booxx you photograph the letter and usually within a few seconds you get an explanation and a full translation in the language you use the software in (Dutch, English, Polish, Hungarian or Romanian), with the amount, the payment date and the last day to object listed separately. It is an explanation, not a sworn translation and not tax advice: objecting is something you do yourself or with your accountant.
Why do I get a blue envelope?
That is the envelope in which the Belastingdienst, the Dutch tax office, sends its paper post: tax return letters, assessments, additional assessments and fines. If you choose digital post, part of those letters arrive in the Berichtenbox of MijnOverheid instead.
How long do I have to object?
Six weeks from the date on the assessment or additional assessment. If you are too late, you can still request a reduction. You cannot object to a provisional income tax assessment; you change it.
I got a naheffingsaanslag because I forgot my VAT return. Do I have to pay the full amount?
Not always: the amount is an estimate. File the return after all. If your VAT is lower than the estimate, pay the € 82 fine, the VAT from your return and a 3% late payment fine (at least € 50), using the payment reference of the naheffingsaanslag; the Belastingdienst then adjusts the additional assessment. If your VAT is higher, pay the full naheffingsaanslag; a new one follows for the rest.
Why is the date on my letter in the future?
The Belastingdienst prints and sends letters before the date on them, so that you have them in time. Deadlines such as the objection period count from the date on the letter.
What does a late VAT return cost?
If the return arrives more than 7 days after the deadline, or not at all, the fine is € 82. If you pay late, the fine is 3% of the amount paid late, at least € 50 and at most € 6,709. If you pay within those 7 days and paid the previous return on time, you get no fine but a notice of default.
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