Annual Quantity correction process

Find out when and how to request an AQ correction. Learn about what happens at the end of the process.

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    What to do before making an AQ correction request

    Before requesting an AQ correction, you should take the steps set out below. These will help you assess whether correction is needed or the right action to take.   

    Check you have submitted a recent meter reading

    If you’ve submitted a recent meter reading, check that it was accepted and in line with the site’s read history. Make sure: 

    • you haven’t transposed any digits 
    • you haven’t mixed it up with another meter 
    • it doesn’t have an incorrect Through the Zeros (TTZ) count. This is also known as a “Round the Clock” indicator 

    Check the calculated volume

    Make sure the calculated volume looks correct. Check if there’s a problem with the meter details – for example, is it set up as metric instead or imperial, or vice versa? 

    What to do if any reads are incorrect

    If one or more reads are incorrect, you’ll need to replace them. You’ll also need to:  

    • engage with a previous Shipper if there any data issues in their period of ownership
    • submit another, more recent meter reading. Replacing an old meter reading does not trigger a new AQ calculation 
    What to do if the TTZ count is wrong

    If the TTZ count is incorrect, you’ll need to replace the read with the same index but the correct TTZ count.  

    What to do If the meter details are incorrect

    If the meter details are incorrect, you’ll need to correct them with an RGMA flow. You can find out more about Review of Gas Metering Arrangements (RGMA) on our e-learning materials webpage.   

    The site may not have a suitable start read between 36 and 9 months before the latest read. If this is the case, keep submitting meter readings. Wait until there’s an eligible pair of meter reads.


    Check you have a valid reason for correcting the AQ

    If you think you need to correct the AQ, make sure you have a valid reason for doing so.  

    There are six valid reasons for correcting the AQ:

    1. Theft of Gas
      Confirmed Theft of Gas means the AQ is too low. This is because the meter wouldn’t have recorded all its usage.

    2. Change in consumer plant
      Evidence of a customer having new equipment fitted means the AQ is incorrect. Additional plant, for example, would consume more gas. Or they may have installed a more efficient boiler.

    3. Commencement of new business
      The site should be new to your portfolio and the AQ incorrect or not in line with its forecasted future consumption. You can only use this Reason Code during the first three months after taking on the site. Additionally, the site shouldn’t have been with any other company within your group (an “affiliate”) before it came to you.​

    4. Tolerance change​
      Meter readings may be rejected if they fail the “outer tolerance” (also known as the “market breaker tolerance”). You should have received read rejections before using this Reason Code. A meter reading is mandatory.​

    5. Erroneous AQ based on read history
      You can use this code within twelve months of your registration date if the site's AQ increases by 100% and greater within your ownership owing to incorrect Meter Read and/or Meter Asset data on UK Link prior to your supply.

    6. Erroneous AQ Change in operation and/or use

    This code can be used if a change in operation or use has impacted a site's current forecasted consumption/Annual Quantity.


    How to submit an AQ correction request

    AQ correction requests must be submitted electronically by the current Shipper: 

    • via the IX network 
    • using the .AQI type   

    For each correction, you’ll need to submit:

    • a separate C41 record 
    • a U01 record to provide a meter reading if you’re using Reason Code 4 
    Accessing our secure file and record formats

    You can find our file and record formats in the UK Link document secure area. All UNC parties are entitled to access this secure internal network.   

    If you haven’t already done so, you can apply for access by visiting our Accessing secure documents webpage.


    When will a corrected AQ go live?

    The new Rolling AQ will go live on the first day of the following calendar month if:

    • we receive the .AQI file before close of business on the 15th working day before the end of the month 
    • the request is not rejected 

    Accepted requests received after the cut-off will go live on the first day of the second following calendar month.  

    Why an AQ correction request may be rejected

    We need to check your AQ correction request and may reject it if:

    • the requesting Shipper is not the registered Shipper 
    • the request has been made using an incorrect file format  

    When we reject a request, we assign a reason code. You can find our Shipper Rejection Codes in the UK Link document secure area. You can apply for access by visiting our Accessing secure documents webpage. 

    We send our responses via the IX network. These are .AQR files, which consist of individual C43 records showing whether the request was accepted or rejected.


    Other changes following an AQ correction

    When we accept an AQ correction request, there are other changes that take place:  

    • The Formula Year AQ will change from the same date the new Rolling AQ goes live.  
    • If the new AQ causes the site to be assigned to a new End User Category, this will take effect on the same day. 
    • If the new AQ takes the site over the threshold to be read monthly, the meter read frequency will be automatically updated on the same day. 

    How the AQ “backstop” prevents future problems

    If we accept an AQ correction, this sets a “backstop” date of the day on which the new AQ goes live. This stops the monthly AQ process from using any meter readings prior to the go-live date of the corrected AQ. Doing so would undo the correction.   

    The AQ backstop is the earliest date for which meter readings can be used to calculate AQs.   

    The site won’t get a new AQ for at least nine months unless you submit another AQ correction.

    More about AQ correction

    View our AQ e-learning course in our learning hub.

    Visit e-learning
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