Money-back letters (GTB)

Dutch Tax and Customs Administration

The Tax Administration wants to help citizens claim tax refunds in an accessible way when they may be entitled to them. The Money Refund Letters (GTB) algorithm automatically selects which citizens are eligible. They will receive a message about it.

Last change on 3rd of June 2025, at 12:13 (CET) | Publication Standard 1.0

• Publication category: Impactful algorithms
• Impact assessment: Field not filled in.
• Status: In use

General information

Theme

Public finance

Begin date

Field not filled in.

Contact information

[e-mail]

Link to publication website

https://over-ons.belastingdienst.nl/onderwerpen/omgaan-met-gegevens/algoritmeregister/

Link to source registration

https://over-ons.belastingdienst.nl/onderwerpen/omgaan-met-gegevens/algoritmeregister/geldteruggaafbrieven-gtb/

Responsible use

Goal and impact

The Tax Authority aims to help citizens claim tax refunds in an accessible way when they may be entitled to do so.

Based on available data, it assesses annually which citizens are presumably entitled to a refund of previously withheld wage tax. These citizens are alerted to the possibility of filing a tax return. This is done by letter. There is no legal obligation: the letter is intended as a service to citizens.

The algorithm automatically selects which citizens qualify for this message. The assessment is based on predefined selection rules and data from various administrations. The sending of the letters is fully automated.

This message is part of the broader process in which the Tax Administration assesses annually who should or can be approached around the income tax return.

Considerations

The Money Refund Letters (GTB) process is important for informing citizens about a possible tax refund in a timely and proactive manner. We want to do this carefully. The algorithm can support a Tax Administration employee in doing so. As a result, the assessment is more careful, efficient and uniform.

The algorithm contributes to the systematic and accurate checking of tax data. By using an algorithm, these assessments can be processed faster. As a result, citizens can get clarity faster.

The algorithm determines the assessment based on the relevant data.

The alternative is for an employee to manually collect and assess the data in all cases. This would make the process more error-prone and less efficient.

Human intervention

Human intervention in the Tax Administration context implies that a competent and knowledgeable employee plays a substantial role in decision-making.

In the operation of the algorithm, there is no human intervention. The algorithm makes the decisions. The purpose of the algorithm is to select citizens who are alerted to a possible refund, and automatically send the GTB.

Risk management

A risk with this algorithm is that citizens may receive a letter while there turns out to be no return in the end. This may lead to confusion or making an unnecessary declaration.

This risk is mitigated by carefully designed selection criteria, regular evaluation of the functioning of the algorithm and clear communication in the letter about the non-binding nature of the notification.

Legal basis

1. General State Tax Act:
2. General Administrative Law Act:
3. General Data Protection Regulation:
4. General Data Protection Regulation Implementation Act:
5. Payroll Tax Act 1964:
6. Income Tax Act 2001:
7. Citizens' Service Number (General Provisions) Act:
8. Archives Act 1995:

Links to legal bases

• Algemene wet inzake rijksbelastingen:: https://wetten.overheid.nl/BWBR0002320/
• Algemene wet bestuursrecht: : https://wetten.overheid.nl/BWBR0005537/
• Algemene verordening gegevensbescherming: : https://wetten.overheid.nl/BWBR0040940/
• Uitvoeringswet algemene verordening gegevensbescherming: : https://wetten.overheid.nl/BWBR0040940/
• Wet op de Loonbelasting 1964:: https://wetten.overheid.nl/BWBR0002471/
• Wet Inkomstenbelasting 2001:: https://wetten.overheid.nl/BWBR0011353/
• Wet algemene bepalingen Burgerservicenummer:: https://wetten.overheid.nl/BWBR0022428/
• Archiefwet 1995: : https://wetten.overheid.nl/BWBR0007376/

Elaboration on impact assessments

The use of the data should be assessed against the AVG.

The AVG prescribes that no more data should be used than necessary. This is called data minimisation. The Inland Revenue regularly reviews whether the data used is still necessary and therefore may be used.

Operations

Data

1. Identifying data (national) identification number/BSN
2. Wage, pension and benefit data
3. Data from previous income tax returns (financial data and personal data)

Links to data sources

• Identificerende gegevens (nationaal)-identificatienummer/BSN: Basisregistratie Personen (BRP)
• Loon-, pensioen- en uitkeringsgegevens: Loon-, pensioen- en uitkeringsgegevens Werkgevers, uitkeringsinstanties en pensioenuitvoerders
• Gegevens uit voorgaande aangiften inkomensheffing (financiële gegevens en persoonlijke gegevens): Belastingdienst

Technical design

The algorithm consists of selection rules drawn up by content experts based on laws and regulations and practical experience.

Based on available data, the algorithm determines which taxpayers may be entitled to a cash refund. These citizens will then automatically receive a letter alerting them to the possibility of filing a tax return.

The outcome of the algorithm is:

- The citizen receives a letter about possible refund;

- The citizen does not receive a letter.

The algorithm is not self-learning. That means it does not evolve itself while in use.

External provider

The algorithm was developed by Tax Administration staff and is also maintained internally.