Software Developers: updates to Corporation Tax guidance and forms
Use this guidance to create your products if you're a HMRC software developer or substitute form producer.
Only use this guide if you’re a software developer or substitute form producer.
CT600 forms versions 2 and 3
HMRC publishes all the forms currently in use on these pages and identifies them by the letter ‘P’ in Draft Corporation Tax (CT) forms: summary for software developers.
To help you prepare your changes, drafts of forms not yet published, identified by the letter ‘D’, will appear in the table as soon as HMRC prepares them. No substitute forms should be published or brought into use based on drafts. HMRC asks you to wait until they publish the final versions, identified by the letter ‘P’ in the table, before seeking substitute approval and publishing your version.
Changes following 2021 Spring Budget
As a result of the Chancellor’s 2021 Spring Budget some changes will be needed to CT systems and processes. The following sections summarise the main CT specific measures that may have an impact on IT systems and processes.
Rates of Corporation Tax: CT main rate
As announced at Budget, legislation has been introduced in the Finance Bill 2021 to set the charge to Corporation Tax and the main rate to 25% for the financial year beginning 1 April 2023.
If an accounting period ends after 1 April 2023, the company should not submit its Company Tax return until the system has been updated.
Company Tax returns for accounting periods starting on or after 1 April 2023 with zero tax chargeable (nil returns) can still be submitted online, as the tax rate change has no impact.
Find out more about changes to Corporation Tax rates from 1 April 2022.
Corporation Tax: Increase in the rate of Diverted Profits
This measure will increase the rate of Diverted Profits Tax from 25% to 31% for the financial year beginning 1 April 2023.
This will maintain the current differential of 6% between the Diverted Profits Tax rate and the main rate of Corporation Tax when the rate of Corporation Tax increases to 25% for the financial year beginning 1 April 2023.
No changes to the CT600 or CT600 guide are needed.
Find out more about the change to the Diverted Profits Tax rate from 1 April 2023.
Corporation Tax: Small Profits Rate
As announced at Budget, the Finance Bill 2021 will be updated to introduce a small profits rate of 19% for financial year April 2023. The small profits rate will apply to profits of £50,000 or less.
Companies with profits between £50,000 and £250,000 will be taxed at the main rate of 25% but will be able to claim marginal relief. These thresholds are proportionately reduced for the number of associated companies and for short accounting periods.
If an accounting period that ends after 1 April 2023, the company should not submit its Company Tax return until the system has been updated.
New boxes will be introduced to the CT600 in 2023. The CT600 guide will be amended to reflect the change. CT computation taxonomy changes will also be made.
Find out more about Corporation Tax charge and rates from 1 April 2022 and Small Profits Rate and Marginal Relief from 1 April 2023.
Temporary extension of carry back of trading losses
This measure has temporarily extended the period over which incorporated businesses may carry back trading losses from one year to 3 years.
This extension will apply to a maximum £2,000,000 of unused trading losses. The £2,000,000 maximum applies separately to unused trading losses made by companies, after carry back to the preceding year, in relevant accounting periods ending between 1 April 2020 and 31 March 2021 and a separate maximum of £2,000,000 for periods ending between 1 April 2021 and 31 March 2022.
The £2,000,000 cap will be subject to a group-level limit, requiring groups with companies that have capacity to carry back losses in excess of £200,000 to apportion the cap between its companies.
No changes to the CT600 or CT600 guide are needed.
Find out more about temporary extension to carry back of trading losses for Corporation Tax and Income Tax.
Super-deduction and 50% first-year allowances (badged in this summary as capital allowance measures)
As announced at Budget, between 1 April 2021 and 31 March 2023, companies investing in qualifying new plant and machinery will benefit from new first-year capital allowances.
Under this measure, investments in main-rate assets will be relieved by a 130% super-deduction, whilst investments in assets qualifying for special rate relief will benefit from a 50% first-year allowance.
New boxes will be introduced to the CT600 in 2022. The CT600 guide will be amended to reflect the change. CT computation taxonomy changes have also been made and are available from August 2021.
Find out more about new temporary tax reliefs on qualifying capital asset investments from 1 April 2021.
Freeports: Enhanced Structures and Buildings Allowance (badged in this summary as Freeport measures with enhanced capital allowances)
As announced in the Freeports bidding prospectus published on 16 November 2020 and at Budget, an enhanced rate of Structures and Buildings Allowance (SBA) will be introduced.
Budget announces the location of 8 English Freeports. Once designated tax sites within these Freeports have been confirmed, the enhanced rate of SBA of 10% will be made available in the designated tax sites after tax site designation for corporation tax and income tax purposes. To qualify, the structure or building must be brought into use on or before 30 September 2026.
New boxes will be introduced to the CT600 in April 2022 as well as a new CT600M supplementary page. The CT600 guide will be amended to reflect the change. CT computation taxonomy updates will also be made.
Find out more about enhanced structures and buildings allowances in Freeports.
Freeports: Enhanced capital allowances (badged in this summary as Freeport measures with SBA)
As announced in the Freeports bidding prospectus published on 16 November 2020 and at Budget, a 100% enhanced capital allowance will be introduced.
Budget announces the location of 8 English Freeports. Once designated tax sites within these Freeports have been confirmed, this enhanced relief will be made available for companies investing in plant and machinery in the designated tax sites. This change will have effect for investment incurred on or after tax site designation until 30 September 2026.
New boxes will be introduced to the CT600 in April 2022 as well as a new CT600M supplementary page. The CT600 guide will be amended to reflect the change. CT computation taxonomy updates will also be made.
Find out more about enhanced capital allowance for plant and machinery in Freeports.
Identical tax returns
Accurate facsimiles of Company Tax Return forms (based on the final paper format) can be accepted providing they meet certain requirements. The output must replicate the HMRC version of the CT600 and supplementary pages for layout, pagination and graphical elements.
Any other CT forms must be centrally approved by HMRC before they’re marketed or brought into use by contacting: hmrc.substituteformsapproval@hmrc.gov.uk.
Draft versions of CT forms
HMRC provides draft versions of the developing Company Tax return forms and supplementary pages on the internet to help software developers and substitute form producers to create their products.
These versions may be subject to some minor amendments during proof reading, but any changes will be shown in the final versions published on the website.
Draft versions have no legal status and are not in a prescribed form. They must not be used by companies to deliver their Company Tax returns.
Drafts are only available for software developers and substitute form producers.
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Last updated 23 September 2020 + show all updates
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The identical tax returns section has been updated as the output must replicate the HMRC version of the CT600 and supplementary pages for layout, pagination and graphical elements.
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The page has been updated with the addition of information on identical tax returns and removal of information on substitute tax returns.
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This guide has been updated with changes following the 2020 Spring Budget.
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This guide has been updated with changes following the 2018 Autumn Budget.
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Following the 2017 Autumn Budget, this page has been updated to include detail of the main changes that will affect a company’s Corporation Tax return and Self-Assessment.
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Updates made following 2016 Autumn Statement announcement.
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Updates made following March 2016 Spring Budget announcement.
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Updates made following July 2015 Summer Budget announcement.
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First published.