How Do I Complete a Corporation Tax Return?

How Do I Complete a Corporation Tax Return?

Daniel Hall 21/02/2024
How Do I Complete a Corporation Tax Return?

Whether preparing to file your first Corporation Tax Return or moving away from a paid accountant to take the DIY approach, it can be quite a daunting prospect.

The process of submitting your return and supporting documents is a lot less complicated than many people think.

Here’s all you need to know about successfully submitting your Corporation Tax return.

Things to Know Before Starting Your Corporation Tax Return


Before filing a Corporation Tax Return, also known as a CT600, business owners must first know when they are due. The return must be filed with HMRC within 12 months of an accounting period’s end date and subsequently paid within nine months of the filing date.

The deadline is linked to the date of incorporation. If you launched a company on 10th August 2023, your first corporate Tax Return will be due on 31st August 2024 with subsequent submissions coming at the end of August each year.

Meanwhile, when completing your Corporation Tax Return online, it is best to use a dedicated software package - not least because it will have guides and customer care support.

What’s Included in the Corporation Tax Return 

Knowing what’s included in the Corporation Tax Return will certainly help. It should include the key company details along with details of how much tax is due, any losses claimed, and any capital allowance. 

As well as the CT600, you will also need to prepare the following;

  • Statutory accounts - profit and loss statement, balance sheet, director’s report.

  • Corporate Tax calculation - a document with adjusted profits for tax purposes.

How to Prepare the CT600

Knowing that the Corporation Tax Return form needs to be submitted is one thing, but preparing it is another. After accessing the CT600 form, you will notice that there are a lot of sections but the majority are fairly simple to complete, especially if you have tax return software to guide you.

The key sections of the document are; 

  • Company information - including the company number and tax registration number.

  • About this return - confirming the dates of the accounting period, and confirming details like whether it includes estimated figures or relief from an earlier period is included. 

  • Tax calculation - the total turnover for the accounting period.

  • Income - this section covers trading profits, any losses brought forward, and further details about income from various sources.

  • Chargeable gains - gross and net chargeable gains.

  • Profits before deductions and relief - including on-trade deficits on loan relationships.

  • Deductions and reliefs - including management expenses, capital allowances, non-trading losses on intangible fixed assets, group relief, and more.

  • Tax calculation - covering the amount of profit, tax rate, and total tax.

  • Reliefs and deductions in terms of tax - including community investment tax relief and double taxation relief.

  • Coronavirus support - covering CJRS entitlements and payments.

  • Energy profits levy - covering oil and gas, as well as EOGPL.

  • Calculation of tax outstanding or overpaid - including Net Corporation Tax liability, bank levy payable, restitution tax, and more.

  • Tax reconciliation - including creative tax credit, total land remediation, and other features.

  • Exporter information - covering goods and services.

  • Indicators and information - including exempt ABGH distributions.

Other sections include; Research and Development (R&D) or creative enhanced expenditure, Land remediation enhanced expenditure, Allowances and charges in the calculation of trading profits and losses, Allowances and charges not included in the calculation of trading profits and losses, Qualifying expenditure, Losses, deficits and excess amounts, Overpayments and repayments, and a Declaration.

In the ‘about’ section, some of the answers may also require you to complete additional forms. For example, insurance requires form CT600D while cross-border royalties require form CT600H.

Filing your Corporation Tax Return to HMRC


When filing your Corporation Tax Return to HMRC, you must first ensure that you have a valid user ID with HMRC. You will also need an account with Companies House as accounts must be filed there too. While the latter can be done via paper submissions, it makes sense to file it digitally - especially when your filing software allows you to do this with minimal effort.

Assuming that you have already prepared your Corporation Tax Return, filing it is as simple as completing the following steps;

  • Sign into your tax filing software.

  • Check that you have selected your business and connected it to HMRC.

  • Upload your Corporation Tax Return and supporting documents.

  • Complete a digital signature. 

  • Review your filing documents and enter your HMRC credentials.

  • Submit the documents.

Following this, you will receive an email to confirm that the form has been submitted. You can also check that it has been accepted and subsequently see the status of any payment made via the HMRC website.

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Daniel Hall

Business Expert

Daniel Hall is an experienced digital marketer, author and world traveller. He spends a lot of his free time flipping through books and learning about a plethora of topics.

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