WOZ valuation with model-based valuation

Municipality of Almere

Every year, we determine the value of all homes in Almere. Each house then receives a WOZ value. We use a calculation model (the algorithm). This enables us to determine all values more quickly. It also ensures that we determine the values of all homes using a standard process.

Last change on 20th of May 2026, at 11:18 (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

02-2025

Contact information

[e-mail]

Link to publication website

Welkom | Level Software & Consultancy

Responsible use

Goal and impact

Level's software is called LEVEL and is a comprehensive ICT system specially designed for municipalities and local tax organisations to fully digitise and automate the processes surrounding WOZ valuation, appraisal, taxation and collection. Based on an algorithm, the system supports and automates the processes surrounding WOZ valuation, appraisal, taxation and collection.

Within the municipality of Almere, this software is used to automatically and uniformly calculate the WOZ value of residential properties. The aim of this processing is to arrive at a consistent and objective valuation, which is then used as the basis for determining the amount of municipal taxes (WOZ levy).

Considerations

Prior to the commissioning of LEVEL's software, the Municipality of Almere made a careful assessment regarding the deployment of the software. This included assessing necessity, proportionality, reliability and the impact on data subjects. Based on this consideration, it has been determined that the use of the algorithm is appropriate for supporting the WOZ valuation.

The alternative to this algorithm is to calculate the value completely by hand. Due to the large number of properties, this is very time-consuming. It also increases the risk of errors. It is better to use the algorithm because it ensures less manual work. With that, we have more time for checks. It is also important to treat equal cases equally. This is better done by following a standard process, which we can automate. This way, we ensure that the burden is shared fairly among residents.

Human intervention

Although the software provides for an automated calculation of the WOZ value, there is always the possibility of human intervention. Municipal employees can assess, check and, where necessary, correct the results of the algorithm. Affected parties always have the possibility to lodge an objection against the amount of the WOZ calculation. In case of such an objection, an employee of the municipality will reassess the calculation.

Risk management

When deploying a property valuation algorithm, careful risk management is essential to ensure that the outcomes are reliable, legitimate and explainable. The main risk relates to incorrect or incomplete determination of the WOZ value, which can lead to unjustified tax assessments and negative consequences for stakeholders.

To manage these risks, several safeguards are applied by the software supplier. Also, homeowners can always object to the level of WOZ value, after which there will always be meaningful human intervention.

Legal basis

Property Valuation Act (WOZ)

Link to Processing Index

Verwerkingsregister Gemeente Almere

Operations

Data

Address details of the property

Property type (e.g. flat, terraced house, detached)

Area (living space, plot size)

Year of construction and any renovations

Location (neighbourhood, area, amenities)

Cadastral data

Sales prices of comparable properties (reference objects)

Market figures and property trend data

Characteristics such as state of repair, quality and facilities