2022 District Valuation Data

National district valuation roll (DVR) data, from a collection provided to Landcare Research by Headway Systems. DVR data includes information describing land, improvement, and capital values for ratings units; as well as council zoning, and actual property use according to the LINZS30300 specification (Rating Valuations Rules 2008: version date 1 October 2010).

Contact Glenn Hughes, Director, Headway Systems if you are interested in more information about the raw data that underlies the derived data which forms this collection. The raw data is aspatial; the added value in this collection is the association to parcels (geospatial polygons), although ultimately much data is published in raster format as a derived product.

Actual data is stored in DataStore with restricted access.

Property valuation

Who does property valuations in New Zealand?

Local councils undertake rating valuations, and they often contract valuation service providers (VSP) like QV. Property valuations are done by registered valuers.

— LINZ

When rating valuations occur

Local authorities carry out property valuations to help determine your annual property rates. Rating valuation notices and rates demands are issued by local authorities. Valuations occur at least every three years. Contact your local authority about their revaluation schedule or for your current rating valuation.

— LINZ

Re-rating

Headway Systems noted that the country is divided into thirds (40%:30%:30%) for the purposes of re-rating, on a three-year cycle. However, many of the anticipated re-rating dates were missed or postponed by councils due to COVID-19 in the 2020–2022 period, which has affected this dataset's underlying information, presumably with more out-of-date information than would have otherwise been the case.

Historical valuations

Headway Systems were contracted by Landcare Research to supply historical valuations dating back to 2013. They did so. However, historical records have so far been ignored, because there is no robust process for associating a title to a parcel or parcels at a particular point in time. That is, a title in 2013 referred to a particular parcel or parcels, but if it was later subject to subdivision, the historical association from title to parcel(s) is lost—LINZ only provides present-day title-parcel associations for download.

Therefore, at present, only current valuations are provided in this collection. (Current to the data supply date.) LINZ is actively seeking to make its historic title-parcel association available, so this may change in the future.

Property titles, and property parcels

The original data from Headway Systems was cleaned and then associated to LINZ parcels, using property titles as a foreign key. One valuation unit may have one or more property titles, and a property title may have one or more associated parcels. The title-parcel association is performed by LINZ, who make this data available in an "evergreen" fashion: https://www.linz.govt.nz/land/land-records/types-land-records/property-titles-and-plans

The title-parcel association data was downloaded to a file when DVR was obtained, as a point-in-time record in order to correctly perform the spatialisation of the DVR.

Data cleaning

The data from Headway Systems underwent considerable data cleaning. Most of this effort went into cleaning the certificate of title information for each rating unit.

Some ratings units did not have a certificate of title at all, and had to be omitted because they could not be spatialised. However, many of these omitted records did have a positive land or improvement values, a land-use or zoning noted by the valuer, a street address and a recorded size (area). The inclusion of a street address implies that it may be possible to locate such records in a limited fashion, but this possibility has not been explored.

There are two formats of valid property title:

• "Paper-era": taking the form CB33A/1277, where CB is a two-character region code, 33A is the alphanumeric prefix, / is a mandatory separator, and 1277 is the numeric suffix, in this example.
• "Electronic-era": a simple integer, e.g. 528017.

The electronic-era format is easier to reconcile, but the raw data is subject to a high degree of uncleanliness, including:

• Electronic-era titles that still improperly include region codes.
  • These can be stripped,
• Electronic-era titles that still attempt to include region codes and alphanumeric prefixes.
  • These often appear to have been automatically populated, e.g. the title 773562 is recorded as 0/0/773562. These can be stripped.
• Invalid region codes.
  • There is a set collection of such regions.
  • Some valuers appear to use numbers instead of characters to represent the region.
• Missing region codes.
  • Missing region codes can be added if necessary, because districts are noted separately.
  • However, the underlying districts have changed since the titles were issued, so this is can only be performed imperfectly.
• Lists of titles separated by many different separator characters.
  • e.g. CB33A/1277 CB33A/1278, CB33A/1277; CB33A/1278
  • However, some valuation units with multiple titles list these in an inconsistent manner, making separation difficult.
    • e.g. CB 33A/1277 CB 33A/1278. (Naïve whitespace is not a reliable separator.)
    • e.g. CB 33A/1277 33A/1278. (CB is implied to apply to all following titles.)
• The use of globally-invalid characters in titles.
  • Only letters, numbers, and a single / character are valid for "paper-era" titles. Regex: (?:^((?:NA)|(?:SA)|(?:TN)|(?:GS)|(?:WN)|(?:HB)|(?:NL)|(?:MB)|(?:CB)|(?:WS)|(?:OT)|(?:SL)){1}(PR)?([\w\d]+)\/([\w\d]+)$)|(^\d*$)
  • At the beginning of a "paper-era" title, only a valid two-character region code may be used; but many titles use additional symbols (RT, CT, RA, etc.) to communicate additional information (cancelled title, etc.) that is not part of the title. However, a PR following the region code is valid.

A (proprietary) processing script was written by the author to validate, clean, and then re-validate (cleaned) titles. Titles that were subject to cleaning were validated at the end of the process; if they were still invalid, they were discarded. A valid title is not a guarantee that the title is correct, and this is even more likely to be the case when a previously invalid title is transformed into something that is valid. Thus while effort has been put into cleaning this data, there is no guarantee of complete correctness, and random error is difficult to quantify or qualify. Just under 33% of all titles underwent transformation in order to pass validation.

Note that since a rating unit may have multiple titles, often most property titles were valid, and a minority of property titles were invalid. This is a partial spatialisation, and such records are included in the output. This may upwardly bias property values when expressed per unit area, however this was considered a valid tradeoff since in rural areas there may be ratings units with many titles, and only a fraction of these were invalid — to lose the whole record due to this would have biased values in the other direction, due to a bias of omission. Additionally, this would have made land-use and zoning more incomplete than necessary.