Are you unsure how to submit Corporation Tax return for your limited company? One of a UK company’s primary obligations is to submit a Corporation Tax return. That is why you must complete the process accurately to avoid penalties, incorrect tax calculations, and HMRC compliance issues.
Completing a CT600 form is only one part of filing a company tax return. The most important part is preparing accurate company accounts, determining your taxable profits, and submitting the required information to HMRC using the appropriate filing method.
With the most recent changes to HMRC’s online filing process, it is also important to use the approved method for submitting your return. Knowing the right process helps you stay compliant whether you are filing for the first time or improving your current process.
This guide outlines the entire process, including filing, submitting your Corporation Tax Return, key deadlines, and much more. So let’s get into it.
Whether you’re just starting or already earning online, we’ll guide you with simple, honest advice tailored to your situation so you can focus on what you do best.
What Is a Company Tax Return?
Before learning how to submit Corporation Tax Return, you first need to understand what a company tax return is. A Company Tax Return is the document that a company submits to HMRC to report its taxable profits and determine its Corporation Tax liability for a specific accounting period.
Moreover, the return includes the CT600 form, company accounts, Corporation Tax calculations (tax computations), and any supplementary pages needed for the company’s circumstances. These details help HMRC understand how the company determines its taxable profits.
Remember that the filing of annual accounts with Companies House is separate from the submission of a Company Tax Return. Although both use information from the organisation’s financial records, they serve different purposes and have different filing deadlines.
Key Takeaways: One major change is that, from April 1, 2026, HMRC closed its previous online support for filing Company Tax Returns. Companies that are required to submit a return must now use recognised commercial software or an authorised agent to submit their CT600 and supporting information electronically.
Who Needs to Submit a Corporation Tax Return?
Now that you better understand the company tax return, it is important to know who must submit a corporation tax return and how to submit Corporation Tax return. Below is a list of some organisations that may need to submit a Company Tax Return (CT600) to HMRC:
- Limited companies are required to submit a Company Tax Return upon receiving a Notice to Deliver a Company Tax Return from HMRC.
- If your company has made a loss, has no Corporation Tax liability, or is dormant, it must still submit a return if HMRC requests it. This is true even if the company has no profit or Corporation Tax to pay.
- Some unincorporated associations, organisations, and societies may also be required to submit a Company Tax Return to HMRC upon receiving a notice.
Who Does Not Need to Submit a Corporation Tax Return?
When learning how to submit Corporation Tax Return, it is important to know who does not need to submit one. Not all businesses are required to submit a Corporation Tax Return to HMRC. Sole traders and standard partnerships report their business income through self-assessment, as they do not submit a Corporation Tax Return UK.
Depending on the circumstances, other business structures, such as limited liability partnerships (LLPs), have distinct tax regulations. They should confirm the specific filing obligations for their structure with HMRC.
What Information Do You Need Before Filing a Corporation Tax Return?
Before submitting a Corporation Tax Return (CT600), companies should have essential business information, accounting records, and tax information for the relevant accounting period. Here is the information you need before submitting a Corporation Tax Return.
- Company information, including the registered name, company number, and HMRC Unique Taxpayer Reference (UTR)
- The accounting period covered by the return Company accounts, including the profit and loss account, balance sheet, and relevant notes.
- Accounting records supporting income, expenses, payroll, and other business transactions
- Corporation Tax computations that show adjustments from accounting profit to taxable profit
- Details of any capital allowances, losses, or tax reliefs that you can claim
If you want to learn how to reduce Corporation Tax, check out: How to Reduce Corporation Tax Legally: UK Guide for Limited Companies (2026)
How to Submit Corporation Tax Return Step by Step?
When discussing the Corporation Tax return, it is helpful to know how to submit Corporation Tax return in the UK.
Prepare Your Company Accounts
Begin by preparing your company’s accounts for the relevant accounting period. These should accurately document your business income, expenses, assets, liabilities, and profit or loss. Additionally, your accounts provide the starting point for calculating your Corporation Tax position.
Calculate Your Taxable Profit
Another important step in how to submit Corporation Tax return is to calculate taxable profit. Before calculating Corporation Tax, it may be necessary to make adjustments to your accounting profit. Taxable profit is not always the same as accounting profit. Tax adjustments may be required for items such as disallowable expenses, capital allowances, losses and available tax reliefs. Remember, these adjustments help determine your company’s taxable profit.
Prepare Tax Computations and Complete the CT600
Once you determine taxable profit, prepare the Corporation Tax computations showing how you calculated the figures. The CT600 form requires company information, the accounting period, taxable profits, tax calculations, and any relevant claims. You may need additional supplementary pages, depending on the company’s circumstances.
Submit the Return Using Approved Software
You must submit Corporation Tax Returns electronically using commercial software recognised by HMRC. The submission typically comprises the CT600, company accounts, and tax computations in the appropriate format, such as iXBRL when applicable.
How To Submit CT600 in the UK?
When understanding how to submit Corporation Tax return, it is also essential to know how to submit CT600. To file a CT600 in the UK, you must either complete your Company Tax Return using HMRC-recognised commercial software or hire an accountant to file on your behalf. Furthermore, the CT600 submission, company accounts, and Corporation Tax computations are typically included.
Complete the CT600 with the correct company details and tax information, calculate your taxable profit, and prepare your accounts before filing. Keep in mind that you must submit the CT600 electronically using software of your choice.
When Is the Deadline for Submitting a Corporation Tax Return?
When exploring how to submit Corporation Tax return, you also need to understand the Company Tax Return deadline. Corporation Tax filing deadline is 12 months after the end of the accounting period. However, the deadline for paying Corporation Tax is earlier. Companies generally need to pay any Corporation Tax due 9 months and 1 day after the end of their accounting period.
What Happens If You Submit a Corporation Tax Return Late?
If you don’t submit a return by the deadline, HMRC typically assesses a late-filing penalty, starting with a fixed amount. Moreover, if the return remains outstanding for an extended period, HMRC may impose additional penalties.
From 1 April 2026, the late-filing penalty rules include an initial £200 penalty for a return filed one day late, plus an additional £200 if it remains outstanding after three months. If a company has a history of repeated late filings, penalties may be increased.
Struggling to Understand How to Submit Corporation Tax Return?
If you are still unsure about how to submit Corporation Tax Return, do not worry; we have got you covered. At Influencers Accountants, our accountants can help prepare your accounts and review Corporation Tax calculations. We also help you complete your CT600 and submit your return on time.
Contact us and get professional support today to streamline the Corporation Tax filing process and ensure that your business fulfils its tax obligations.
Avoid last-minute surprises by seeing your costs upfront, so you can plan better, stay in control, and make smarter financial decisions.
The Bottom Line
Understanding how to submit Corporation Tax return correctly helps companies fulfil their HMRC obligations and avoid unnecessary penalties. Each step is essential to ensuring compliance, from preparing accurate accounts and calculating taxable profits to submitting the CT600 and the required information on time.
When businesses have multiple transactions, tax relief claims, or changes in their financial circumstances, Corporation Tax rules and filing requirements can be complex. By keeping accurate records throughout the year and seeking professional help when needed, you can submit your Corporation Tax Return by the required deadlines.
Disclaimer:
The information in “How To Submit Corporation Tax Return: A Complete Guide for UK Companies” is for general guidance only and does not constitute professional tax or legal advice. Always consult a qualified accountant for your specific situation.
