06 January 2026

This release note provides information about the release of the AddressBase Core product on 06 January 2025.

AddressBase Core planned Christmas downtime

The AddressBase Core product was not refreshed on the week commencing 29 December 2025 due to planned downtime. Customers with Change-Only Update (COU) orders did not receive any change for that week. Updates have resumed following the AddressBase Core product refresh schedule on the week commencing 05 January 2026 and will include 2 weeks’ worth of change.

Record counts

Product	Full Supply Record Count	Change-Only Update Record Count
AddressBase Core	34 816 979	13 723

Please note that the Full Supply record count is based on a Managed Great Britain Set (MGBS). If you ordered your national coverage via the online ordering system using a polygon outline, your counts may differ.

Product supply comparison

There is a difference in record counts between taking a national Managed Great Britain Set (MGBS) and the national 5km tile supply. This is because the two supplies use different selection criteria. The difference in record counts is shown in the following table, allowing you to validate your data holdings once you have loaded the latest release of AddressBase Core.

Product	MGBS Full Count	National 5km Tiled Supply	Difference
AddressBase Core	34 816 979	34 816 965	14

A small difference in record counts is expected due to there being several features supplied in the MGBS which fall outside of the tiled area.

Changed records

If you receive a Change-Only Update (COU) supply for your AddressBase Core product, you will receive Insert, Update and Delete records within the supplied file. The following table details the numbers of these records which can be expected in the COU supply of the product:

Change Type	Count
Inserts	2 048
Updates	11 350
Deletes	325
COU populated 5km tile count	1 828

It's important that COUs are processed with Deletes first, then Inserts and Updates. This is to ensure that updates are applied in the correct order. Further guidance on this can be found in 'Working with COU data' in the AddressBase Getting Started Guide.

Source data currency

The following information relates to the currency of the source data used in the creation of this release of AddressBase Core:

Data Source	Date
Royal Mail Postcode Address File (PAF)	01 January 2025
National Land and Property Gazetteer	01 January 2025
One Scotland Gazetteer	07 December 2025
OS MasterMap Topography Layer	18 December 2025

Known data issues

Details of data issues, service disruptions and planned maintenance for AddressBase Core will be communicated on the AddressBase Core Data Issues, Service Disruption and Planned Maintenance page; this page will provide details of the impacts of any data issues, plus updates on the expected time frame for resolution.