Algorithm Gate checks

Dutch Tax and Customs Administration

This page contains information about the 'Gate checks' algorithm. The Gate checks algorithm checks data from the payroll tax return on entry before they are actually processed by the Tax and Customs Administration. The algorithm makes it possible to identify discrepancies in data and notify the submitter of the payroll tax return.

Last change on 4th of July 2025, at 8:25 (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/poortcontroles/

Responsible use

Goal and impact

The Tax Authority checks withholding agents for correct and complete declaration and payment of payroll taxes. Payroll taxes consist of wage tax, national insurance contributions, employee insurance contributions and the income-related Healthcare Insurance Act contribution. Withholding agents (such as an employer, pension fund or benefits agency) withhold wage tax and national insurance contributions from their employee's wages and, in some cases, the income-related Healthcare Insurance Act contribution. They remit this to the Tax Office. The employee insurance contributions and usually the income-related Healthcare Insurance Act contribution are not deducted from the employee's salary, but are paid by the employer to the Tax Administration.

A withholding agent periodically submits a wage tax return with employee data to the Tax and Customs Administration. The employee data focuses on the individual employee, consisting of personal data, income relationship, wage data and wage tax to be withheld. In addition, the withholding agent also indicates the total amount of payroll taxes to be withheld.

After receiving the payroll tax return, the Tax and Customs Administration performs automated checks. These checks are performed at the gate, using the Gate Check algorithm. Before the data from returns are actually processed. The payroll tax returns are assessed on a number of points so that the Tax and Customs Administration can process the returns. The starting point is the prescribed gate inspections in the 'Payroll tax return data specifications'. The gate checks consist of technical, validation and consistency checks and are described in sections 2.6.1 to 2.6.3. of the Data Specifications.

The Data Specifications for payroll tax returns are published annually on the Tax and Customs Administration's site: https://www.belastingdienst.nl/wps/wcm/connect/bldcontentnl/themaoverstijgend/brochures_en_publicaties/gegevensspecificaties-aangifte-loonheffingen

Considerations

The algorithm performs checks before data is actually processed by the Tax Administration's systems. In case of error messages in these checks, the submitter receives a message in response. An error message results in rejection of the payroll tax return by the Tax and Customs Administration. The submitter of the payroll tax return must correct the error after which the payroll tax return can be submitted again. The submitter may be the withholding agent itself or a payroll administrator.

The algorithm guarantees an accepted quality of certain data and processability of these data in systems. Based on the instructions from the algorithm, a check takes place automatically and without human intervention. The check relates to prescribed specific parts of data, as described in the document Data specifications payroll tax return.

Assessing data is important for withholding agents so that they arrive at correct administrative processing of their data in data sources. The algorithm can provide automated support to the Tax Administration in this regard.

Human intervention

In the operation of the algorithm, there is no human intervention. The algorithm makes the decisions. The purpose of the algorithm is to ensure data quality and processability in systems.

Risk management

The General Administrative Law Act (Awb) requires the government's actions to be transparent and lawful. The Tax Administration observes the general principles of good governance when applying and developing algorithms.

The algorithm uses data collected under various tax laws. As required by the AVG, no more data is used than necessary.

The selection rules are reviewed periodically and adjusted if necessary to remain compliant with laws and regulations.

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. Social Insurance (Funding) Act:
7. General provisions Citizen Service Number 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://eur-lex.europa.eu/legal-content/NL/TXT/HTML/?uri=CELEX:32016R0679
• Uitvoeringswet algemene verordening gegevensbescherming: : https://wetten.overheid.nl/BWBR0040940/
• Wet op de loonbelasting 1964:: https://wetten.overheid.nl/BWBR0002471/
• Wet financiering sociale verzekeringen:: https://wetten.overheid.nl/BWBR0017745/
• Wet algemene bepalingen Burgerservicenummer:: https://wetten.overheid.nl/BWBR0022428/
• Archiefwet 1995: : https://wetten.overheid.nl/BWBR0007376/

Elaboration on impact assessments

• Privacy and AVG

The use of data is tested against the General Data Protection Regulation (AVG). Reviewing personal data reveals any privacy risks and allows appropriate measures to be taken.

The AVG prescribes that no more data should be used than necessary. This is called data minimisation. The Tax Administration regularly examines whether the data used are still necessary and may therefore be used.

• Use of special personal data

The Gate Checks algorithm does not use special personal data.

• Equality and non-discrimination

The algorithm is assessed in line with applicable non-discrimination principles for direct and indirect discrimination. Processing as little personal data as possible reduces the risk of direct discrimination. Employees involved in developing and managing the algorithms receive training on data protection and bias.

Operations

Data

• Identifying data (LH number)
• Payroll tax details
• Payroll tax return details

Links to data sources

• Identificerende gegevens (LH-nummer): Belastingdienst
• Relatiegegevens Loonheffingen: Belastingdienst
• Aangiftegegevens Loonheffingen: Belastingdienst

Technical design

The algorithm consists of conditions and checks established by content experts based on laws, regulations and expertise.

The algorithm is not self-learning. That means it does not evolve as it is used.

External provider

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