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Company Accounts & Corporation Tax: Essential Facts Every UK Director Must Know

If you run a limited company in the UK, you have two separate sets of compliance obligations: filing accounts with Companies House and dealing with Corporation Tax through HMRC. These are related but distinct requirements, with different deadlines, different forms, and different consequences for missing them.

This guide from CIGMA Accounting answers the most common questions company directors have about annual accounts and Corporation Tax in clear, practical terms.

Does Every Limited Company Have to File Accounts?

Yes. Every limited company registered at Companies House must file annual accounts, regardless of whether it made a profit, a loss, or had no activity at all.

Dormant Companies

Dormant Companies 

A dormant company (one with no significant accounting transactions) files dormant accounts rather than full statutory accounts. This is a simplified form, but it is still mandatory. Failing to file – even as a dormant company – results in penalties. 

What Is the Difference Between Companies House Filing and HMRC Filing?

These are two entirely separate obligations: 

  • Companies House – you file your company’s statutory annual accounts and a Confirmation Statement (CS01). This is public information, visible to anyone. 
  • HMRC – you file a CT600 Company Tax Return, along with your accounts and tax computation. This details your taxable profits and Corporation Tax due. 

 

Both sets of documents are usually prepared from the same underlying accounts but submitted to different bodies with different deadlines. 

What Are the Key Deadlines?

  • Companies House accounts: within 9 months of accounting period end
  • HMRC CT600 filing: within 12 months of accounting period end
  • Corporation Tax payment: 9 months and 1 day after accounting period end

The key point is that the payment deadline comes before the HMRC filing deadline, which often causes confusion for directors.

What Happens If You Miss the Companies House Deadline?

Companies House imposes automatic penalties for late filing:

  • Up to 1 month late: £150
  • 1 to 3 months late: £375
  • 3 to 6 months late: £750
  • More than 6 months late: £1,500

These penalties double if you file late two years in a row for the same company. There is no discretion – HMRC (and Companies House for accounts) cannot waive a penalty simply because you have a good reason, though you can appeal in exceptional circumstances. 

Persistent failure to file can result in Companies House striking off your company – dissolving it. 

What Happens If You Miss the HMRC CT600 Deadline?

HMRC applies penalties for late filing of the Corporation Tax return:

  • 1 day late: £100 flat penalty 
  • 3 months late: An additional £100 penalty 
  • 6 months late: HMRC estimates your Corporation Tax due and charges 10% of that estimate 
  • 12 months late: A further 10% of estimated unpaid tax 

If a return is not submitted, HMRC may issue a tax determination based on its own estimate. This cannot be appealed and must be replaced by submitting the actual return.

Can You Check Your Deadlines Online?

Yes. Your company’s filing deadlines, accounting period, and confirmation statement due dates are all visible on the Companies House website.

Your Corporation Tax deadlines can be found in your HMRC Business Tax Account online.

Does the Amount of Profit (or Loss) Affect Whether You Must File? 

No. The obligation to file accounts with Companies House and a CT600 with HMRC exists regardless of your company’s financial performance. Even if your company made no money at all, or incurred a loss, you must still file. Loss returns are important – they establish the losses available to carry forward against future profits. 

How Long After Online Submission Do Accounts Appear on Companies House? 

Online submissions typically appear on the Companies House register within 24 hours. Postal submissions take considerably longer – potentially several weeks – and given the risk of postal delays affecting your deadline, online filing is strongly recommended. 

Make Sure Your Corporation Tax Is Calculated Correctly

At Cigma Accounting, we support businesses across London in understanding how company accounts and corporation tax work together, ensuring reporting is accurate and fully compliant with HMRC requirements. From Fulham Broadway, including Walham Green and Sands End, many directors are unclear how accounting figures translate into tax obligations, which is why our guidance focuses on clarity, accuracy, and practical decision-making.

Company accounts form the foundation of your corporation tax calculation, meaning even small errors in recording income or expenses can impact your final tax position. With physical offices across London, we help businesses maintain reliable financial records, meet filing obligations, and stay fully aligned with UK tax rules.

Frequently Asked Questions

How do company accounts affect corporation tax?

Company accounts form the basis for calculating taxable profits. Adjustments are then made for tax purposes, such as adding back disallowable expenses and applying tax reliefs, to determine the final corporation tax due to HMRC.

Corporation tax is charged on company profits, including trading income, investments, and capital gains. All limited companies must file a tax return annually, and tax must be paid even if profits are retained within the business.

Companies must file annual accounts with Companies House and a Company Tax Return with HMRC. Accounts are typically due 9 months after the financial year-end, while the CT600 return is due 12 months after the accounting period ends.

Company accounts are prepared for financial reporting and Companies House, while corporation tax returns are submitted to HMRC to calculate tax liability. Both use similar data but serve different legal and compliance purposes.

Yes, all active UK limited companies must file a corporation tax return with HMRC, even if they make no profit or owe no tax. This is a legal requirement to remain compliant with UK tax law.

Inaccurate company accounts can lead to incorrect tax calculations, HMRC penalties, and compliance issues. Businesses may also face investigations if errors are significant or appear deliberate.

Company accounts provide the financial foundation for tax planning, helping businesses understand profitability and tax exposure. Accurate accounts allow better forecasting, efficient tax management, and compliance with HMRC requirements.

Keep Your Company Accounts Accurate and Corporation Tax Compliant

Understanding company accounts and corporation tax is key to compliance. We help businesses apply corporate tax basics, manage corporate and income tax considerations, and ensure accurate financial reporting aligned with HMRC requirements.

Get Help With Corporate Tax Basics

Cigma Accounting helps businesses manage company accounts and corporation tax with accuracy, compliance, and practical financial oversight.


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CIGMA Accounting
CIGMA Accounting Ltd is a forward-thinking accounting and tax firm based in London, dedicated to delivering high-quality compliance, tax planning, and business advisory services to entrepreneurs, landlords, and growing SMEs. With offices in Wimbledon and Farringdon, we combine local expertise with a tech-driven approach to simplify accounting. Our services include corporation tax filing, VAT compliance, HMRC investigation support, R&D tax credit claims, capital allowances optimisation, and bookkeeping automation. What sets CIGMA apart is our ability to blend traditional accounting rigour with AI-powered systems that reduce errors, save time, and provide real-time financial insights. Our team ensures that every client - from startups to high-net-worth individuals - receives a bespoke solution aligned with their growth goals. Whether you need strategic tax planning, help with HMRC disclosures, or a full outsourced finance function, CIGMA Accounting delivers clarity, compliance, and confidence.
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