A CT600 return is the name of the filing that UK Incorporated companies must file with HMRC after the end of their accounting period. Currently this is stipulated to be no later than 12 months after the end of the company's Accounting period, with any Corporation Tax payable due after 9 months and a day following the accounting period end. A CT600 can only report up to 12 months, so if the accounting period is longer (an extended accounting period), two CT600's would need to be filed.
The CT600 return is now required to be filed digitally with HMRC, with the original CT600 paper form now obsolete and now only used for the compilers reference. Along with the CT600 return HMRC also require that full company accounts are also provided in a format known as IXBRL, where key information is tagged so that the document can be both machine read and viewed as a normal document. Unlike the CT600 the accompanying Company accounts can cover accounting periods greater than 12 months, that is the full duration of the Accounting period.
The CT600 return is divided into sections which relate to the different activities of the company.
The main sections are:
Other sections include:
Along with the main CT600 return there are also supplementary sections which we won't go into here. The most common is the CT600A for declaring Loans to company officers, but also there are supplementary sections for Tonnage (Boats) and other items that are normally related to Large of medium enterprises.
As mentioned above HMRC require the CT600 return to be filed electronically(or digitally in new terms), through
the HMRC Gateway which is basically a service which enables software platforms like Easy Digital Filings to
connect to and transmit the filing. When using the Easy Digital Filing Service, the end of year amounts are entered
into capture templates which in some ways mimics the old paper CT600 Form. Although with the advantage of a real time
Calculation Engine calculating the Tax position on the Fly. Once the Filings (the Accounts and CT600) are set Ready for
Filing, the Corporation Tax Submission engine takes all of the inputs and creates the Digital representation of the CT600
in an XML structure and then creates an accompanying IXBRL Tagged Computations and Company Accounts. These supporting documents
are base64 encoded, inserted into the CT600 XML structure and cryptographically hashed (the IRMark) for transmission to HMRC.
To be able to make the submission, the filer/Company needs to have a HMRC gateway account (username and password) for its respective Unique Tax Reference (UTR) and also have the CT600/Corporation Tax service Activated for the Gateway Account. If the username, password, UTR are incorrect and/or CT600 service has not been activated, then any submission will be rejected with the (very common) 1046 Error Message.
A simple company that has a very basic set of returnable items may in some cases be bale to use the HMRC CATO (Company Accounts and Tax Online) system to make the digital filing. However due to the narrow set of circumstances that the CATO system provides for most companies will need to file using another service (e.g EasyDigitalFiling).
Examples of companies that have to File using a service like Easy Digital Filing are: