Creating submissions

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You can create both original and amended submissions.

To access Online filing click the Online filing hyperlink in the Actions panel in the left hand navigation panel.

Ensure that the appropriate task permission has been set for the security group.

There are three essential steps to the creation of the submission:

  1. Preparing the return for submission

  2. Attaching accounts, computations and other documents

  3. Pre-validating the submission


The following information explains how to attach documents to the submission.


There is a restriction to the size of each attachment and the total size of the submission.

  • Accounts, computations and other PDF documents cannot exceed 9mb each. (This is on the advice of HMRC)
  • The submission including all attachments cannot exceed 18mb.

If these limits are exceeded Corporation Tax will display a meesage and remove any documents.  

Attaching accounts to the submission

To attach accounts to the submission::

  1. Click on New submission

  2. Attach a set of iXBRL or PDF accounts by clicking on the Load attachment button alongside the field

  3. Browse to the location of the accounts (HTML, PDF)

A PDF set of accounts can only be attached if the company is permitted to do so. This applies to such companies as Clubs and Associations. select the PDF accounts attached with explanation in Main Return Data data entry window
  1. Double click on the file or click on Open button

  2. If you wish to view the file that is attached click on the View attachment button.

  3. Click Delete attachment if you wish to delete the file attached.

If the accounts file has been prepared using CCH Accounts Production then the iXBRL accounts file will be automatically retrieved and attached to the online filing submission when first entering into a submission.

Attaching computations to the submission

The iXBRL computation is automatically generated and attached to the submission.

To attach an external or third party computation

  1. Tick the box called Attach third partyi computation located on the Main Return Data window. 
  2. Select Online filing from the ribbon
  3. Click on New submission from the left hand task bar
  4. Select Add from the ribbon task bar
  5. Select Computation from the list

  1. To view the computation click on the View  option in the ribbon
  2. Select computation from the list

Attaching other documents

When attaching Other Documents note that HMRC apply strict limits to the size of each document and also for the cumulative total size of all documents that are attached and submitted with the CT600 Tax Return.

To attach other supporting documents to the submission

  1. Click on the Load attachment button alongside the field in the Other attachments section. A maximum of 7 PDF files can be attached to a single submission.

  2. If the Other Attachments are larger than the maximum size permitted then a validation message will appear and the document will be removed from the submission.
  3. To remove any or all of the attachments click on the Delete attachment button.
  4. To view the attached files highlight the file(s) and click on the View attachment button.

  5. You can proceed to pre validating the submission



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CCH Corporation Tax




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