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WOZ is the Dutch abbreviation for Valuation of and is derived from the Valuation of Immovable Property Act. This Act regulates the valuation method.

How is the WOZ value determined?

Which characteristics determine the WOZ value?

To determine the WOZ value, we look at:

  • the date on which we determine the WOZ value
  • the characteristics (such as the type, size, construction year, cadastral area and annexes)
  • the market value
  • the market data

What date do we use to determine the WOZ value?

For the tax year 2024, we will use the value on 1 January 2023. This a national scheme. We will also consider the situation of the residence on 1 January of the current tax year (2024).

Questions or disagree with the WOZ value?

Then schedule a call appointment with one of our appraisers. The appraiser explains how we determined the WOZ tax base. And answers your questions about the WOZ tax base. Your appraisal report shows how we determined the WOZ tax base. Is the WOZ tax base incorrect? Then the appraiser can often adjust this right away on the phone. Can you not find a solution with the appraiser? Or is more data needed? Then file an appeal at My RBG. Or use our appeal form WOZ

Explanation of the characteristics

The characteristics

The characteristics of immovable property also determine the sum of the WOZ value. We retrieve the characteristics from construction plans, photos and/or recordings of the immovable property. For residential property, it concerns the following characteristics:

  • the type of house (e.g. terrace house, detached house, apartment)
  • the size of the house
  • the construction year of the house
  • the annexes (garage, storage, extension, conservatory, etc.) and the size thereof
  • the presence of dormer(s)
  • the size of the cadastral plot
  • the location
  • – the state of repair

The size

RBG uses net dimensions (usable area) to determine the WOZ value of residences for the Municipalities of Delft, Vlaardingen and Schiedam. We will compare the net dimensions of your house to the net dimensions of other houses in your Municipality. The usable area is described in the Dutch NEN 2580 standard. All assessors and estate agents use the same Measurement Instructions for the usable area of residential properties.

The market value

RBG redetermines the WOZ value of your house or piece of land every year. We determine this by assessing what your house would fetch if sold on 1 January of the previous year. To this end, we will look at sales prices of similar houses in your municipality.

The market data

We will look at sales prices of comparable houses that have been sold between 1 January, 2022 and January 1, 2024. Were no comparable houses sold during this period? Then we look at previous sales prices. RBG will register and analyse all these sales figures constantly. We use these sales figures to determine the WOZ value for houses that are similar. We will take mutual differences, such as the size, state of repair, land area and location into account. When few sales prices are available, RBG can also use previous market data.

WOZ value for renovation and under construction


If you are renovating, then this will often affect the WOZ value. Did you renovate your house between 1 January 2023 and 1 January 2024? Then the situation on 1 January 2024 will apply to the WOZ value.

Under construction

The amount of the WOZ value for a building under construction depends on the progress of the construction. The WOZ value of a building under construction consists of:

  • The value of the land
  • The part of the building that has been completed on 1 January of the tax year.

Calculation example: The value of the land is € 75,000. If the building is completed, then the value is € 300,000. The construction has been completed for 60% on 1 January. The WOZ value will thus be € 255,000. This is the value of the land (€ 75,000) plus the value of the building (60% x € 300,000).

Supervision by the Valuation Chamber

The Valuation Chamber is the supervisory body that checks whether we are properly implementing the rules of the Valuation of Immovable Property Act (WOZ Act).

We are responsible for the quality of the appraised WOZ value. The Valuation Chamber checks whether we have carefully examined the quality of the valuations. The Valuation Chamber completes this check before we publish the valuations. After the audit, the Valuation Chamber agrees to send out the new WOZ valuations.