This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

COTAX Manual

Returns / notices: return handling: not allocated returns

This subject is presented as follows.



Returns submitted online

A company or agent can change the existing accounting period (AP) structure when submitting a return using the Corporation Tax Online Service. The Government Gateway ensures that:

  • the AP created does not exceed 12 months
  • APs are continuous
  • the new AP entered by the user has at least one day in common with the AP to be superseded.

When COTAX receives the return, it tries to automatically amend the AP structure to fit the dates shown on it. If it is unable to do so, the case is listed on EFRL (E-Filed Returns List) and the return is referred to as not allocated.

Paper returns

When, exceptionally, you receive a paper return that does not match a live AP on COTAX, function LRTN (Log Return) lets you amend the AP structure. If you cannot do so, the case is listed on AAPR (Amend Accounting Period List) and was previously referred to as a mismatch. All guidance relating to not allocated returns relates also to mismatched paper returns.

Not allocated returns

Because COTAX has not been able to process the return and has put it on a work list, you cannot see it in function DRTN (Display Return Details). However, the e-filed return appears in the list of return periods in View CT Returns as ‘not allocated’.

Before you can capture the return and record the self assessment, you need to make any necessary amendments to the AP structure.


Where COTAX treats a return as not allocated, it automatically sets an ‘inhibit penalty’ signal for all APs for which a return is outstanding for that company.

This inhibits the issue of:

  • return reminders and
  • penalty determinations.

See COM101000 for further information.


Every company tax return for an accounting period must include a self assessment of the amount of tax which is payable by the company for that period. A company tax return is regarded as a return for an accounting period if the period is treated in the return as an accounting period and is not longer than twelve months, even though it is not, or may not be, an accounting period in fact.

You can only challenge the validity of the AP provided by:

  • correcting it, if the apparent error comes from a failure to apply the proper principles to be used in arriving at CT APs or
  • opening an enquiry into the return, if the apparent error comes from an incorrect view of the facts.

As a general guide, the caseworker should give authority to correct a return in these circumstances only if:

  • the company or agent acknowledges the existence of a fact that causes an AP to stop or start, but fails to recognise or give effect to the relevant legal principle and
  • you believe that the company or agent will be content to follow your approach, taking account of any implications it may have on the obligation to make a return for some other period or periods.

See COM132035 for further information on the action to be taken.

Top of page


It is possible that the start or finish of a trade will be in question, and the company or agent are unwilling to accept the fact of commencement or cessation, or the date on which the event took place. You can only challenge such cases by opening an enquiry into the return.

If you decide the position can only be dealt with by way of an enquiry, print the return and attachments submitted through the Corporation Tax Online Service.

For those offices using Caseflow or CQI to control enquiry cases, the following are automatically entered and amended on COTAX from those systems:

  • enquiry in progress signal
  • started date and
  • enquiry type.

If your office does not use Caseflow or CQI, you must use function MAPS (Maintain AP Signals) to enter or amend the entries in the above fields and pass the return back to the Clerical Caseworker to log as e-filed with manual intervention, capture the return and record the self assessment. See COM154040 for further guidance.


  • COM132035 for more information
  • COM132011 for a list of forms relevant to this subject
  • COM132021 for a list of functions to use in particular situations
  • COM132022 for legislation applying to this subject.