UK Company Tax Filing 2026: CT600, Annual Accounts & Deadlines

Every UK limited company has two separate annual obligations that often get confused as one thing: a CT600 corporation tax return filed with HMRC, and statutory annual accounts filed with Companies House. These are different documents, sent to different government bodies, with different deadlines — and missing either one triggers automatic penalties regardless of whether your company actually owes any tax. For the current financial year, the corporation tax rate sits at 19% on profits up to £50,000, 25% on profits above £250,000, with marginal relief tapering the effective rate in between. Here's exactly what's required, when it's due, and what changes (or doesn't) if you're a non-resident director running a UK company from abroad.

The Three Filings Every UK Company Owner Confuses

Before anything else, it's worth separating three distinct filings that get lumped together constantly, since each serves a different purpose and goes to a different authority.

The confirmation statement is the one most frequently mixed up with annual accounts, since both go to Companies House and both are annual obligations — but they're entirely separate documents covering completely different information. Our detailed breakdown of confirmation statement vs annual accounts walks through exactly how these two differ if you want the full picture before diving into the tax return side of things.

What Is a CT600 Corporation Tax Return?

The CT600 is the form every UK limited company uses to report its taxable profits to HMRC and calculate how much corporation tax it owes. This gets filed annually, covering your company's accounting period, and it's submitted separately from — though often alongside — your annual accounts.

A few things about the CT600 that catch first-time filers off guard:

• You must file a CT600 even if your company made no profit or a loss. Zero tax owed doesn't mean zero filing obligation — HMRC still expects the return.
• The CT600 requires detailed tax computations, not just a summary of profit — this includes adjustments for capital allowances, disallowed expenses, and any reliefs being claimed.
• Filing must be done in iXBRL format for the accompanying accounts submitted alongside it, which is a specific tagged data format most accounting software handles automatically, but can trip up anyone attempting to file manually without the right tools.
• You can technically file your own CT600, and HMRC provides free online filing for straightforward cases, though the tax computation itself is where most self-filers make costly errors, particularly around capital allowances and marginal relief calculations.

Current UK Corporation Tax Rates

Corporation tax rates operate on a tiered structure that's been in place since April 2023, and remain unchanged for the current financial year:

Marginal relief exists specifically to avoid a sudden jump from 19% to 25% the moment a company crosses £50,000 in profit — instead, the effective rate increases gradually across that middle band. For a company with profits in the marginal relief zone, the effective rate typically lands somewhere around 26.5% on the portion within that band specifically, due to how the relief calculation works, though the blended overall rate on total profit remains between 19% and 25%.

Two details worth flagging since they trip up growing companies specifically: these £50,000 and £250,000 thresholds apply to a standard 12-month accounting period with no associated companies. If your company has an associated company under common control, or a shortened accounting period, both thresholds get proportionally reduced — meaning the higher rate can kick in at meaningfully lower profit levels than the headline figures suggest. These rates are set through the annual Budget process, so it's worth confirming the current corporation tax rate directly with HMRC rather than assuming it stays static year over year.

What Are Statutory Annual Accounts?

Annual accounts (sometimes called statutory accounts) are the financial statements every UK limited company must prepare and file with Companies House each year, regardless of company size or profitability. At minimum, these typically include:

• A balance sheet showing the company's financial position at year-end
• A profit and loss statement (though small and micro-entity companies can often file abbreviated versions)
• Notes to the accounts explaining the figures in more detail
• A director's report (required for most companies, though small companies have reduced requirements)

The exact level of detail required depends on your company's size classification. Micro-entity accounts — for the smallest companies, meeting specific turnover, balance sheet, and employee thresholds — require minimal disclosure and can often be filed without a full profit and loss account being made public. Small company accounts have slightly more detailed requirements but still benefit from reduced disclosure compared to larger companies. Larger companies must file full statutory accounts with complete detail, since the abbreviated options aren't available to them.

Filing Deadlines: What's Due When

This is where the confusion between CT600 and annual accounts becomes most consequential, since the two filings have different deadlines entirely, even though they're often prepared together.

Notice that the corporation tax payment deadline (9 months and 1 day) comes well before the CT600 filing deadline (12 months) — a distinction that surprises a lot of directors who assume the payment and the return are due at the same time. You're expected to estimate and pay what you owe before you've technically filed the return confirming that figure, which means keeping your books current throughout the year matters considerably more than treating tax preparation as a once-a-year scramble.

For your first year as a new company, deadlines work slightly differently, since your first accounting period and your Companies House accounting reference date don't automatically align — first-year accounts are often due 21 months after incorporation rather than the standard 9-month rule, though this depends on your specific incorporation date. If you're navigating this as a new company owner, our Companies House compliance checklist covers the full first-year timeline in more detail.

What Happens If You File Late

Companies House and HMRC penalize late filings independently, and both escalate the longer you wait:

Companies House late filing penalties (for annual accounts) typically scale with how late the filing is — starting at a modest fixed penalty for filings up to one month late, and increasing significantly for delays beyond three months, six months, and beyond. These penalties double if you were also late the previous year, which makes a first late filing considerably cheaper to fix than letting it become a pattern.

HMRC late filing penalties (for the CT600) apply separately and also escalate — an initial penalty applies immediately after the deadline passes, with additional penalties accruing at three months and six months late, and further penalties if the pattern repeats across consecutive years.

Beyond the direct financial penalties, a persistent late-filing pattern with Companies House can eventually lead to the company being struck off the register — a considerably more serious consequence than a fine, since it affects the company's legal existence entirely.

Do Dormant Companies Need to File Accounts?

Yes, and this is one of the most commonly misunderstood aspects of UK company compliance. A dormant company — one with no significant accounting transactions during the period — still must file annual accounts with Companies House, even though the filing itself is simplified (dormant company accounts require minimal disclosure).

On the tax side, if your company is genuinely dormant for corporation tax purposes, you can notify HMRC directly that the company is dormant, which can remove the CT600 filing obligation for that period — but this notification has to be made proactively; HMRC doesn't automatically assume dormancy just because no tax is owed. Skipping this notification step is a common reason dormant company owners end up with unexpected penalty notices despite genuinely having no trading activity.

UK Company Tax Filing for Non-Resident Directors

This is the section most generic UK accountancy content skips entirely, and it's a critical point for Brandora's international audience: filing obligations do not change based on where the director lives. A UK limited company with a non-resident director still owes the same CT600, annual accounts, and confirmation statement obligations as a company run entirely by UK-based directors.

What genuinely differs for non-resident owners isn't the filing requirement itself, but the practical logistics around it — signing authority for accounts, arranging payment of any tax owed from overseas, and in some cases, understanding whether the company's central management and control being exercised from abroad affects its UK tax residency status. If a UK-registered company is genuinely managed and controlled from outside the UK, this can raise separate residency questions under HMRC's central management and control test, which is a more advanced consideration than most straightforward Pakistani- or Indian-owned UK companies need to worry about, but worth being aware of if directors are making major strategic decisions entirely from abroad.

If you're setting up or already running a UK company as a non-resident, our guide on registering a UK company as a non-resident covers the formation side, and it pairs directly with this article's compliance obligations once the company is actually trading.

CT600 vs Self-Assessment: A Distinction Worth Clarifying

Directors sometimes conflate their company's CT600 with their own personal Self-Assessment tax return, but these are entirely separate filings covering different taxpayers. The CT600 reports the company's profit and calculates corporation tax owed by the company itself. Self-Assessment reports the director's personal income — salary, dividends drawn from the company, and any other personal income — and is a completely separate filing with HMRC under the individual's own tax reference, not the company's.

A director drawing dividends from their UK company needs to account for those dividends on their personal Self-Assessment return, in addition to (not instead of) the company filing its own CT600. This is a genuinely common point of confusion for first-time company directors, since both filings happen roughly around the same time of year but serve completely different purposes.

How to Actually File: The Practical Process

For annual accounts:

1. Prepare your financial statements based on your accounting period, matching your company's size classification (micro-entity, small, or full accounts).
2. Submit through Companies House's online filing service, either directly or through accounting software with iXBRL-compatible filing.
3. Confirm receipt and keep records of your submission for your own files.

For the CT600:

1. Calculate your taxable profit, applying any adjustments, allowances, and reliefs your company qualifies for.
2. Complete the CT600 form, along with the required supplementary computations.
3. File online through HMRC's Corporation Tax Online service or compatible software.
4. Ensure any tax owed is paid by the 9-months-and-1-day deadline, separate from the filing deadline itself.

Many companies file accounts and the CT600 together through integrated accounting software, since the underlying financial data overlaps significantly — this is generally more efficient than preparing each filing from scratch independently.

Frequently Asked Questions

What is the deadline for filing UK company accounts? Annual accounts are due at Companies House 9 months after your company's accounting reference date, though first-year accounts often follow a different 21-month-from-incorporation rule. This is separate from your CT600 corporation tax return deadline, which is 12 months after your accounting period ends.

Do I need to file a tax return if my company made no profit? Yes. Every UK limited company must file a CT600 corporation tax return annually, regardless of whether it made a profit, broke even, or recorded a loss. The only way to remove this obligation is to formally notify HMRC that the company is dormant.

What is the current UK corporation tax rate? For the current financial year, companies pay 19% on profits up to £50,000, 25% on profits above £250,000, and an effective rate between the two via marginal relief on profits in that range. These rates are reviewed annually through the Budget process, so it's worth confirming the current rate directly with HMRC.

What happens if I miss the Companies House filing deadline? Companies House applies an automatic late-filing penalty that increases the longer the delay continues and doubles if the company was also late the previous year. Persistent late filing can eventually lead to the company being struck off the register.

Can a non-resident file a UK company tax return? Yes. Filing obligations for CT600, annual accounts, and confirmation statements apply identically regardless of where the company's directors are based. Non-resident directors can file these returns remotely, though some may choose to use an accountant to handle signing authority and payment logistics from abroad.

What is the difference between a CT600 and annual accounts? The CT600 is filed with HMRC to report taxable profit and calculate corporation tax owed. Annual accounts are filed separately with Companies House as a public record of the company's financial position. Both are required annually, but they go to different authorities and have different deadlines.

Bottom Line

Running a compliant UK limited company means treating the CT600, annual accounts, and confirmation statement as three genuinely separate obligations — each with its own deadline, its own recipient, and its own consequences for missing it. The corporation tax rate structure itself is relatively stable and predictable once you understand the 19%/25% split and where marginal relief applies. Still, the filing calendar is where most avoidable penalties actually happen, particularly for first-year companies and non-resident directors juggling deadlines from a different time zone.

If you're managing UK company compliance from outside the UK and want to make sure your CT600, annual accounts, and confirmation statement deadlines are properly tracked rather than risking avoidable penalties, you can book a consultation with Brandora or explore our full business formation and compliance services built for founders managing UK entities internationally.

For official, current filing requirements and deadlines, Companies House's guidance on filing annual accounts and HMRC's Corporation Tax guidance remain the authoritative sources to confirm before filing.