SAM121268 - Returns: individual returns: auto-coding
Source: gov.uk (2025-12-04)


Auto-coding functionality will be introduced from 6 April 2010 to automatically trigger a PAYE tax code following
- Capture of a paper return, either an original or an amendment
Or
- Receipt of an online return, whether and original or an amendment
When returns and amendments for CY-1 are received and processed, the information will be passed to PAYE for auto-coding where
- The return shows a PAYE source of income and there is a PAYE link on the SA record
Or
- The amendment includes employment income, and
- There is no PAYE link on the record, and
- The ‘Final Return Year’ signal is set on the SA record, and
- The final return year is the same as the year of the amended return, and
- There is an automatic note held on the SA record to show the SA record was closed following refinement
Note: No Auto coding updates are sent during the period from the beginning of January to 5 April each year.

Details of the information used in the auto-coding process can be found in the following documents

Auto-coding SA100 2023-2024 (https://www.gov.uk/hmrc-internal-manuals/self-assessment-manual)

Auto-coding SA200 2023-2024 (https://www.gov.uk/hmrc-internal-manuals/self-assessment-manual)

The are two exceptions to this
- Where the SA record is marked ‘deceased’ and the signal is set, no information will be passed to the National Insurance and PAYE Service (NPS)
- Where the item has been updated since the Annual Coding review. In this scenario, auto coding will not overwrite that amount with the amount on the return
Any information relevant to the code shown in the Additional Notes space of the return must be used to update the NPS IABD screen at the time of processing so that NPS can pick this information up.

Information will be sent over to NPS on a daily basis. If a return is amended more than once on the same day, only the information from the latest amendment will be passed to NPS. For further information, see the PAYE Manual at PAYE13150.

Inhibit auto-coding signal

This signal, also known as the Automatic Coding Inhibited (ACI) signal, will exclude the case from auto-coding on a permanent basis and an SA note must be made when the signal is set giving a reason why. The signal will permanently stop any information being passed to NPS whenever a return or amendment is processed.

The ACI signal is only to be used by work areas that have an agreed concession. They will confirm that they have set the signal in an SA Note. If you do not work in one of these business area’s do not set the signal.

When reviewing a record which shows the signal, check SA Notes for confirmation of why the signal has been set and who by. If there is no note and you are unable to find the reason for it, unset the signal.

Note: The use of this signal will cause work list entries to be created so if you have not been authorised to do so, you should avoid setting this signal where another course of action is more appropriate.

More appropriate actions are
- Following the guidance for coding deductions and expenses at PAYE12000 onwards where the customer claims uncertainty as a reason for requesting that the signal should be set
- Removing the customer from Self Assessment where they say they are no longer within SA criteria
- Including the appropriate restriction in the PAYE code. If an appropriate restriction is included in the code, the customer may no longer be required to complete a self assessment return as the auto refinement rules would close the SA record and then the inhibit auto coding signal would no longer be required
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Exceptions

Entries will appear on work list W052 ‘SA/PAYE auto-coding exceptions’ where
- There are discrepancies for NIB and / or underpayments coded
And / or
- The following return pages have been completed
- Minister of Religion
- Member of Parliament, Scottish Parliament, Welsh Assembly or Legislative Assembly for Northern Ireland
And / or
- The inhibit auto-coding signal is set
Where the inhibit auto-coding signal is not set, auto-coding will still take place, even if there is an entry on work list W052.