1 June 2020

Uniform Network Code Modification 678 (UNC0678) and its alternatives aims to deliver more stable, predictable and less volatile charges for customers and to achieve timely compliance with the EU Tariff Code. 

UNC0678 was raised by National Grid on 17th January 2019 and 10 alternatives (678A – 678J) were subsequently raised by the industry.  Ofgem made a decision on the 28th May 2020 that UNC0678A is to be implemented on 1st October 2020.

Below covers the scope of changes introduced under UNC0678A and the impacts on associated systems and processes for industry awareness, and action where required.

High level overview of UNC0678A

Transmission Services (TS)

  • Postage Stamp based Capacity Charges (i.e. one price for Entry Capacity and one price for Exit Capacity) – no geographic variation.  Capacity reserve prices linked to revenue to better facilitate revenue recovery from Capacity Charges.
  • Capacity (except for legacy Entry bought before 6th April 2017) payable prices change year to year
  • No Commodity charges for Transmission Services
  • Any revenue recovery (to manage over or under recovery) will be via a capacity based charge – levied separately to capacity reserve charges and based on bookings
  • Storage Discount to capacity reserve prices of 50%
  • Interruptible discount of 10% from reserve price (Entry and Exit)

General Non-Transmission Services (GNTS)

  • General Non-Transmission Services broadly aligns to SO charges as they stand now recovered mostly via commodity charges, with some exceptions
  • Some targeted charges (e.g. DN Pensions Deficit, St Fergus Compression, Metering) with the remainder recovered by GNTS Entry and Exit Charges

 Impacts of UNC0678A on systems and related processes

  • As a result of UNC0678A there are some systems changes to UK Link and Gemini
  • New Charge Types are being created as a result of the required charging products in line with UNC0678A.
  • The impact to industry of the systems changes includes some new Charge Types on invoices generated from UK Link and Gemini and new File Formats for invoices.
  • There will be changes to two Gemini Screens a) Fully Adjusted Capacity b) Bid Information Report.  Details of these changes will be provided in the Gemini External Screen Pack to be issued separately.
  • The industry was first notified about the systems changes through the Xoserve Change Pack issued on 12th April 2019.
  • Further details of the new Charge Types and File Formats will be included in the Xoserve Change Pack due to be circulated shortly.

Next Steps

Further communications will be available:

National Grid will send out further information to support the external community as it becomes available.


For queries related to the UNC0678 proposals please email Future Markets at box.gsoconsultation@nationalgrid.com

For queries related to the systems and/or process changes please email box.gasops.businessc@nationalgrid.com

Details of the proposals related to UNC0678 can be found on the Joint Office Website.

Share this news article