Corporation Tax Online

2009 Budget, extension of carry back rules

Companies and their agents can amend their Company Tax Return at any time up to 12 months after their filing deadline (known to HMRC as the 'filing date' or 'statutory filing date'). A company’s filing deadline is usually 12 months after the end of its Corporation Tax accounting period.

In the 2009 Budget a temporary extension of the carry back rules for trading losses was announced. Losses arising in accounting periods ending between 24 November 2008 and 23 November 2010 inclusive can now be carried back for up to three years.

In line with the new rules, if you now wish to carry back a loss for an accounting period where the normal time limit for amending a return has passed you will need to contact your Corporation Tax Office in writing to make the claim. HMRC will then review your claim within the revised rules.

You won’t be able to amend your return online.

Accounting periods

Accounting periods - making changes

You can overwrite the period shown on your client's online return. However if you alter the accounting period the system will take the new dates as the basis for the next accounting period.

If no dates are shown on your client's return but you need to alter your client's accounting period (for example the regular accounting period is January to December, but the company ceases trading in June) you will need to contact the HM Revenue & Customs (HMRC) office responsible for your client. HMRC will be able to enter the revised period, and the appropriate dates should appear on your client's return after about 48 hours.

If your client's accounting period exceeds 12 months you will need to log on to Corporation Tax Online and access your client's records to determine the correct action. If only one accounting period is displayed on screen you need to contact the HMRC office responsible for your client. If two are displayed, use the change period option to amend the accounting periods to reflect the actual accounting period involved (which will be one full year plus a part year).

Accounting Period exceeds 12 months

Agents will need to log on to Corporation Tax Online and access their clients' records to determine the correct action. If only one accounting period is displayed on screen you need to contact the HMRC office responsible for your client. If two are displayed, use the change period option to amend the accounting periods to reflect the actual accounting period involved (which will be one full year plus a part year). Only one set of accounts and computations is required.

Change of address

Unincorporated companies and their agents can notify a change of address directly to HMRC. This can be done online if the company/agent is registered to use Corporation Tax Online.

Limited companies must notify Companies House (on form 287 or online) of a change of address of their registered office. HMRC is not able to accept a notification of a change of address unless the Companies House record has been changed. When we receive a notification, we check with Companies House before updating our records. (Companies House doesn't send us any notification of the change).

It's not possible to tell us the new address online, and so the company or its agent must contact us by phone or post. We suggest you wait about ten days after Companies House has been informed to allow time for their record to be updated.

Client filing list

Every month a paper list of companies which need to file a return in that month is generated by our corporate system and issued to agents. This list should contain company details that mirror your online client list. If you are aware of any discrepancies you should contact the Online Services Helpdesk Tel 0845 605 5999.

Company Tax Returns and XBRL

XBRL stands for Extensible Business Reporting Language, which is an international standard designed for business financial reporting.

At the moment accounts and other attachments to online CT600 returns can be sent in PDF format. From April 2011 (and for all CT600 returns due after 31 March 2011) we expect that all CT600 returns will have to be sent online, and will have to include attachments using the XBRL format.

You don't have to wait till 2011 to change to XBRL, and we recommend you consider doing so before it becomes mandatory. Later in 2009-10 HMRC intends to introduce a CT filing product which uses XBRL (this will be aimed at smaller, unrepresented companies), and to introduce a new main CT Online service. Other software developers have introduced or are working on products which use XBRL.

For more information on XBRL access the link below.

File and manage your Corporation Tax Account Online

Joint filing facility with Companies House - updated September 2009

HMRC and Companies House have issued a statement about progress towards developing an optional joint filing facility.

Go to the HMRC and Companies House joint statement

Online Company Tax Returns – Budget Changes

Following the Budget each year, changes have to be made to form CT600. We can't finalise the form or revisions to the Corporation Tax Online Service until after the Finance Bill becomes law, and until any relevant Regulations are effective. It may still be possible to file returns before this time, but if you need to do so please refer to the guidance on our website.

Guidance - CT600 Forms

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