The Dutch tax authorities always and only communicate through paper mail and/or through your personal portal on the website belastingdienst.nl - which can be accessed with Digid. 

Messages through other forms of communication (whatsapp, text messages, e-mail, social media) are fake and scam. The bank account number of the Dutch tax authorities to transfer money into can be found on their website

Because of the fact that correspondence from Belastingdienst is in Dutch, it is often unclear why it is sent, what it means and if any action is required. Therefore, we listed the subject of the most common letters from the Dutch tax authorities below, including some details and instructions with respect to liabilities (if action is required).
 

Before a Dutch income tax return is filed

Aangifte doen voor de inkomstenbelasting

• invitation to file a Dutch income tax return
• if you receive this invitation, you are obliged to file a Dutch income tax return
• deadline is mentioned in the letter (usually before May 1 of the year following to the concerning tax year)

Herinnering (= urgent) – 1st reminder for filing a tax return 

Aanmaning (= very urgent) – 2nd reminder for filing a tax return – extension is no longer possible, penalty applies if tax return is not filed within the stated deadline

Dwangbevel (immediate action required) – applies when not responded to “aanmaning”, no extension, 3 days to respond penalty and additional costs will be charged
 

After a Dutch income tax return is filed

uw aangifte inkomstenbelasting 

• This could mean that the type of income tax return filed, differed from what the Dutch tax authorities expected, based on residency information (migration date facts sometimes differ from municipality registration details)
• Action: facts are leading, so usually a request needs to be filed to the Dutch tax authorities to change the residency in their systems. Sometimes, the income tax return needs to be adjusted and re-filed

verzoek doorgeven bankrekeningnummer

• The Dutch tax authorities do not have your bank account details for a tax refund that is waiting for you. 
• Action: you need to register your bank account with the Dutch tax authorities in order to receive the refundable result of your income tax return. If you can login into your portal at belastingdienst.nl with Digid and you have an iban account number, you can arrange this online. If not, you are required to file a letter with the Dutch tax authorities. Instructions can be found here..
   

Voorlopige Aanslag inkomstenbelasting/premies volksverzekeringen

• is often issued after filing an income tax return, usually within 3 months after filing date
• can also be issued after filing of a preliminary tax return (optional - if you expect a refund or a payable amount, you can have the (estimated) finances settled up front, during the year)
• can also be issued if the result of your previous year’s tax returns has been a payable amount. In that case the Dutch tax authorities make an estimation for the new year

Voorlopige teruggaaf

• is issued after filing of a preliminary tax return in which you claimed decuction for the principal residence and/or personal deductions. 
• can also be issued if you received a preliminary assessment (up front settlement) in the previous year. In that case the Dutch tax authorities make an estimation for the new year

Aanslag inkomstenbelasting/premies volksverzekeringen

• is normally issued if an income tax return is filed, after Dutch tax authorities audited/approved the return. With the final assessment, the tax year is closed. Usually the final assessment is issued within a year after filing, but sometimes the Dutch tax authorities take more time. In a normal situation, the Dutch tax authorities formally may take 3 years to finalize the tax year.
• if no tax return was filed and the reminders were missed, such final assessment can be issued on the basis of an estimation. If the assessment is too high, you can object and provide the tax return. If too low, you still are obliged to report your income and pay the actual tax liability. 
• If the preliminary assessment was in accordance with the income tax return filed, the final assessment should amount to nil. If the preliminary amount paid or refunded up front differs from the result of the income tax return, the difference is usually settled when the final tax assessment is issued.
• Note that sometimes after filing an income tax return a final tax assessment is issued without preliminary assessment was issued.
   

Voorlopige aanslag ZVW (Zorgverzekeringswet)

• A contribution health care Act (Zorgverzekeringswet / ZVW) is normally an employer contribution to the Dutch social security system, paid through payroll wage tax. If there was no Dutch payroll (in case of freelanze work or foreign employer with no Dutch payroll), the ZVW contribution is due by the taxpayer.
• After a tax return is filed in which income is reported that is not payroll processed in a Dutch payroll, a preliminary ZVW assessment is issued 

Aanslag ZVW (Zorgverzekeringswet)

• the final Assessment for Health Care Act contribution is issued after the Dutch tax authorities audited the income tax return.

If a Dutch tax consultant is involved with tax return preparation

Formulier registratie machtiging intermediair goedkeuren 

• After a tax consultant registers as your tax service provider with the Dutch tax authorities, you will receive this letter. You can activate the Power of Attorney by scanning the QR code.

Aanvraag Activeren machtigingsregistratie Servicebericht Aanslag door uw intermediair 

• after a tax consultant applies for SBA machtiging, the Dutch tax authorities send you a form in which you can grant the Power of attorney by scanning the QR code. The page with the QR code also holds a code, which your consultant requires to activate SBA. With SBA, your consultant should receive a digital copy of tax assessments that are send to you on paper by the Dutch tax authorities.

Aanvraag Activeren machtigingsregistratie  Servicebericht Toeslagen door uw intermediair 

• after a tax consultant applies for SBT machtiging, the Dutch tax authorities send you a form in which you can grant the Power of attorney by scanning the QR code. The page with the QR code also holds a code, which your consultant requires to activate SBT. With this SBT, your consultant should receive a digital copy of Beschikking Toeslag (Allowances) that are send to you on paper by the Dutch tax authorities.
   

* Gegevens van de vooraf ingevulde aangifte voor mijn intermediair - 

• After  we apply for "VIA", you will receive a letter with a 9 digid code, which we can use in our software to get access to information that the Dutch tax authorities received from employer, financial institutions, local authorities etc. If you share the code, we can download such data from the Dutch tax authorities into our software. If you do not want that, you can chose to not share the code.
   

Doorlopende machtiging

• This letter confirms that the registration of a tax consultant for undefined period (rather than one year). No action required, can be cancelled at any time.