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
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. Companies that are moving from dormant to active status should also be aware that costs incurred before trading begins may qualify for tax relief our guide on pre-trading expenditure for companies explains what qualifies and how to treat these costs correctly in your first return. Companies operating in property development with offshore elements face a separate set of registration and reporting requirements that sit alongside the standard Companies House and HMRC obligations. If your company falls into this category, read our guide on how to register an offshore property developer for Corporation Tax to ensure your filing structure is correctly set up from the outset.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. Understanding exactly which profits are included in your taxable figure is equally important our guide on which profits count for UK companies explains the different income streams that form part of your Corporation Tax calculation.
What Are the Key Deadlines?
- Companies House accounts: within 9 months of accounting period end, Read our step-by-step guide on how to pay Corporation Tax online to ensure your payment is made correctly and reaches HMRC on time.
- HMRC CT600 filing: within 12 months of accounting period end
- Corporation Tax payment: 9 months and 1 day after accounting period end
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
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
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. Beyond loss reporting, understanding the full scope of what your company tax return must include from profit adjustments to relief claims is essential for every director. Read our complete guide on company tax return obligations for a detailed breakdown. For a full step-by-step guide on how taxable profits are calculated including how losses and adjustments are treated our guide on calculating taxable income for companies walks through the complete process with a worked example.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.Company Accounts, Corporation Tax, and HMRC Reporting Requirements
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 Farringdon, including Moorgate and Angel, 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.
One area that is often overlooked is whether the company’s activities formally qualify as a trade for tax purposes our guide on the meaning of trade for tax purposes explains how HMRC assesses this and why the distinction matters for your accounts and tax return.
To understand the most common points of failure in a company tax return and how an accountant safeguards your submission against them, read our dedicated guide on avoiding costly errors in your company tax return.
