Corporation Tax is one of the cornerstones of the UK tax system. It touches nearly every incorporated business – from small local firms to global multinationals with UK operations. For accountants, it is a familiar but often evolving area of compliance, planning and advisory work.

This guide is designed to give you a thorough and practical overview of Corporation Tax. We’ve written it with accountants in mind, but with enough narrative and examples to help you explain Corporation Tax concepts to clients in simple terms. We’ll explore:

• Who has to pay Corporation Tax
• Current Corporation Tax rates and thresholds
• How and when to register to pay Corporation Tax
• How Corporation Tax is calculated
• Available tax reliefs and allowances (with practical scenarios) for Corporation Tax
• Corporation Tax filing and payment requirements
• Common Corporation Tax pitfalls and how to avoid them.

Who has to pay Corporation Tax?

Corporation Tax applies to limited companies on their taxable profits. If a client operates as a sole trader or partnership, Corporation Tax does not apply, and they’ll generally pay income tax and national insurance contributions through a self-assessment tax return instead. That said, it’s useful to understand the rules of Corporation Tax either way, as moving from self-employment to a limited company structure can change the tax position significantly.

Entities that pay Corporation Tax include:

• UK-registered limited companies
• Foreign companies with a UK branch or office
• Clubs, co-operatives and unincorporated associations (e.g. community sports clubs, trade associations).

The scope of Corporation Tax is intentionally broad. Essentially, any incorporated entity earning taxable profits in the UK is brought into the net and will pay Corporation Tax.

For accountants, this means you will often encounter Corporation Tax obligations even when advising charities with trading subsidiaries, not-for-profit clubs, or overseas groups setting up UK branches. Understanding the breadth of applicability – essentially, who has to pay Corporation Tax – is the first step to advising correctly.

Corporation Tax rates and thresholds

Companies that pay Corporation Tax are charged on taxable profits, not turnover. Profits include trading income, investments and chargeable gains. There are different Corporation Tax rates. The current system has three tiers:

• Small profits Corporation Tax rate – for companies with profits at or below a defined lower threshold, taxed at a reduced rate
• Main Corporation Tax rate – for companies above the upper threshold, taxed at the headline rate
• Marginal relief – for companies between the Corporation Tax thresholds, tapering the effective rate.

Why this matters in practice

Clients sometimes assume they pay Corporation Tax at a flat rate – either they “get the small rate” or they “pay the big one.” Walking them through marginal relief calculations (and how group structures affect thresholds) is one of the most practical teaching roles accountants take on.

How do you register for Corporation Tax?

Newly incorporated companies must register for Corporation Tax within three months of starting to trade. “Trading” is defined broadly – it can include employing staff, advertising or renting premises, not just buying and selling products and services.

The process involves:

1. Registering the company at Companies House via a business account
2. Receiving the Unique Taxpayer Reference (UTR) (you’ll need to register a business account with HMRC and create a username and password for this)
3. Creating a Government Gateway account and registering with HMRC for Corporation Tax.

In practice, many people choose to register with Companies House and HMRC at the same time and often use an accountant to help them far in advance of paying Corporation Tax. It might also be necessary to register for payroll with HMRC at this point.

Failing to register on time can trigger penalties, so it’s worth making this part of your client onboarding checklist.

How do you calculate Corporation Tax?

As part of clients’ compliance with Companies House, they’ll have to file a set of accounts which includes a profit and loss account, a balance sheet, notes and a directors’ report – as a minimum.

As their accountant, you’ll help explain that calculating Corporation Tax is not simply a matter of applying a rate to accounting profits. The Corporation Tax calculation involves:

1. Starting with accounting profit from the company’s statutory accounts
2. Making adjustments for disallowable expenses (e.g. client entertaining)
3. Claiming capital allowances, reliefs and deductions
4. Arriving at taxable profits
5. Applying the appropriate Corporation Tax rate.

Corporation Tax filing requirements

When it comes to Corporation Tax filing, companies must file annual accounts with Companies House. You’ll usually submit clients’ Corporation Tax return (known as a CT600) along with iXBRL-tagged accounts. The Corporation Tax return and payment are typically due nine months and one day after the end of the company’s accounting period (with exceptions for very large companies paying by instalments).

What are the deadlines for Corporation Tax?

Corporation Tax operates on strict timelines:

• Filing the CT600 – 12 months after the end of the accounting period
• Paying Corporation Tax – nine months and one day after the end of the period
• Large companies – may need to pay their Corporation Tax bill in quarterly instalments.

Missing Corporation Tax bill deadlines results in penalties and interest. Even minor lateness is penalised. Advising clients to plan ahead – and using software to set reminders – is one of the simplest ways to add value.

Is there any tax relief available for Corporation Tax bills?

Yes, there are several tax reliefs available, and Corporation Tax planning revolves largely around tax reliefs and allowances. These can reduce clients’ Corporation Tax liability significantly, but only if used correctly. Remember, businesses only pay tax on profit (not turnover) – and if they make losses in one year, they can be carried forward to offset profits in future years.

Capital Allowances

Capital Allowances are a type of tax relief designed to allow companies to deduct the cost of qualifying plant and machinery from taxable profits.

Example – A café upgrading equipment
A small café spends £12,000 on a new espresso machine and kitchen ovens. Under the Annual Investment Allowance (AIA), the café could deduct the full £12,000 from profits in the year of purchase. For a business with £30,000 profits, that deduction could reduce taxable profits to £18,000, slashing the Corporation Tax bill.

As an accountant, explaining the timing of purchases is key. Buying equipment just before year-end, rather than just after, can bring forward the corporate tax benefit.

Research and Development (R&D) relief

R&D tax relief rewards companies engaged in innovation by lowering their Corporation Tax liability. The definition of R&D is broader than many clients expect – it includes developing new processes, improving products, or solving technological challenges.

Example – A software start-up
A small tech company develops a bespoke algorithm to process client data more efficiently. Even if the project is not commercially successful, it qualifies as R&D. If it makes a loss, it may even receive a cash credit.

Your role is to help clients identify qualifying projects, as many underestimate their eligibility.

Loss relief

Companies making a trading loss can carry it forward to offset against future profits, carry it back to claim a refund, or in some cases surrender it to group companies.

Example – A new manufacturer
A company incurs £80,000 of losses in its first year due to high set-up costs. In its second year, it makes £120,000 profit. By carrying forward the loss, taxable profit falls to £40,000, ensuring the company stays in the small profits band. This not only reduces the Corporation Tax bill – it also stabilises cash flow in the crucial early years.

Pension contributions

Employer contributions to pension schemes are deductible for Corporation Tax purposes.

Example – A consultancy owner
A director-owned consultancy contributes £10,000 into the director’s pension. The payment reduces the company’s taxable profits by the same amount, lowering Corporation Tax while building retirement savings.

This is a straightforward example of tax planning that benefits both business and owner.

Other tax reliefs

• Creative industry tax reliefs (for film, TV, theatre, video games)
• Patent Box regime (reduced tax on profits from patented inventions)
• Group relief (surrendering losses within a group of companies)

As an accountant, you don’t have to memorise every tax relief or scheme. The value you can bring is to help clients spot when an activity might impact or reduce their Corporation Tax bill and then guide them through the claim process.

Common Corporation Tax pitfalls and how to avoid them

Corporation Tax compliance is full of small but costly traps. Clients can often see their accountant as the safety net, but that role can also become reactive if these pitfalls aren’t anticipated. Here are the areas where mistakes most often occur, and how you can help clients steer clear of them.

Confusing types of business profit

Many directors assume that the bottom-line figure on their business profit and loss account is the amount they will be taxed on. They don’t appreciate that Corporation Tax is calculated on tax-adjusted profits.

For example, a company might record £100,000 trading profit, but if £5,000 was spent on client entertaining (disallowable) and £15,000 qualifies for capital allowances, the taxable profit is £90,000, not £100,000.

How to avoid it: Walk clients through at least one example calculation each year, showing the adjustments. Even if they don’t remember every detail, they’ll grasp that the tax bill is not a straight percentage of the accounts.

Missing registration deadlines

New companies must register for Corporation Tax within three months of trading. The broad definition of “trading” means many directors miss the trigger – for instance, paying for adverts or hiring staff before they make their first sale.

How to avoid it: Build registration into your client onboarding checklist. If you offer company formation services, register for Corporation Tax at the same time as Companies House incorporation.

Overlooking reliefs and allowances

It’s surprisingly common for businesses to under-claim reliefs – particularly R&D, capital allowances, and pension contributions. Clients often assume these are only for “big” companies or tech firms, when in reality, many SMEs qualify.

Example: A small craft brewery improves its fermentation process and assumes it’s “just part of the job.” In fact, it may qualify for R&D relief.

How to avoid it: Encourage clients to describe projects or purchases in their own words. You can then translate their activity into tax terminology and spot opportunities.

Late filing and payment

Penalties for late filing for Corporation Tax start small but escalate quickly. Interest on late payments is another unnecessary cost. Even a one-day delay creates reputational headaches for clients.

How to avoid it: Use accounting software or practice management tools to set automated reminders for both you and the client. Position timely filing as part of good financial hygiene, not just compliance.

Inconsistent record-keeping

Disorganised records create headaches for both client and accountant. Missing invoices, unclear expense claims, or lump-sum entries make it harder to calculate accurate tax and risk overpaying or under-claiming reliefs.

How to avoid it: Encourage cloud-based accounting software, and train clients in basic habits like scanning receipts or tagging expenses. Position this as a way to save them money at year-end.

Misunderstanding loss relief options

Clients often fail to make the best use of trading losses. Some leave them unclaimed, while others don’t realise they can carry losses back for a refund.

How to avoid it: Proactively raise loss relief options when discussing year-end accounts. A short conversation could free up much-needed cash for a struggling business.

By anticipating these pitfalls, you move from being the person who “fixes mistakes” to the adviser who prevents them. That distinction often defines the strength of client relationships.

Corporation Tax as part of advisory work

Too often, clients think of Corporation Tax as an unavoidable tax bill that arrives once a year. As their accountant, you have the opportunity to shift this mindset – showing them that Corporation Tax can be a planning tool rather than a pure cost.

Positioning Corporation Tax in business strategy

Corporation Tax touches on almost every strategic decision: how to pay directors, whether to invest in equipment, when to expand, how to fund growth. By framing tax as part of these discussions, you help directors make choices that are both commercially sound and tax-efficient.

Example: A company debating whether to lease or buy vehicles will find the decision looks very different once capital allowances, cash flow and Corporation Tax rates are factored in.

Using Corporation Tax as a conversation starter

The annual CT600 is not just a filing obligation – it’s a chance to review the entire year. You can use the Corporation Tax return as a springboard for advisory conversations:

• Why were profits higher or lower this year?
• Did we make the most of available reliefs?
• Are there investments we should plan before the next year-end?
• How does the tax liability affect dividend planning?

These conversations deepen client relationships and often lead to broader advisory engagements.

Helping clients see the bigger picture

Clients often fixate on the size of their tax bill. Reframing the discussion can change their perspective:

• A higher tax bill means higher profits – a sign of growth
• Reliefs and allowances can reduce the amount of Corporation Tax paid, but the priority is always sustainable profitability
• Corporate Tax is not separate from the business – it reflects its success and direction

By helping clients interpret their Corporation Tax bill in context, you build trust and provide reassurance.

Building advisory services around Corporation Tax

Corporation Tax can underpin wider services, such as:

• Cash flow forecasting – factoring in tax liabilities to avoid surprises
• Business structuring – advising on group structures, associated companies, or incorporation
• Exit planning – preparing for disposals and managing chargeable gains
• Growth planning – modelling how expansion will impact tax bands and cash flow

Each area begins with Corporation Tax but extends into broader advisory support.

Technology and forward planning

Modern Corporation Tax software and cloud accounting tools mean that forecasting Corporation Tax is easier than ever. Accountants can produce “what if” scenarios in minutes, showing clients how decisions today affect their liability tomorrow.

For example, you might demonstrate how a £20,000 equipment purchase shifts taxable profit into the small profits rate, or how accelerating R&D spending this year creates a cash repayment. Visualising these outcomes makes tax planning tangible for directors.

From compliance to partnership

Ultimately, moving beyond compliance transforms your role. Instead of being the person who files the CT600, you become the partner who:

• Helps clients avoid pitfalls before they happen
• Frames Corporation Tax in the context of wider goals
• Shows opportunities to reduce the amount of Corporation Tax paid, reinvest or grow
• Uses each tax year as a chance to reflect and plan ahead.

This is where accountants add the most value – not just processing numbers, but making sense of them.

Corporation Tax can feel daunting to clients, but with the right guidance it becomes a manageable and even strategic part of running a business. For accountants, this is where technical knowledge meets client care: explaining rules clearly, identifying opportunities, and keeping businesses compliant.

Use this guide as a framework for conversations with clients. Walk them through who pays a company tax return, how their Corporation Tax liability is calculated, what reliefs are available and how Corporation Tax deadlines work. Share examples that reflect their own situation. And always remind them: the Corporation Tax bill is not just a number to pay – it is a number they can influence, with your advice.

The post Corporation Tax | A Beginner’s Guide appeared first on capium.

Proper planning can mean significant tax savings and improved financial health for your clients, and the complexities of the UK tax system mean that the professional guidance of an accountant is essential.  

At Capium, we’re here to empower accountants with the tools you need to offer that expert advice. Here are some top tax planning tips for 2024 to share with your clients. 

Take advantage of the Annual Investment Allowance (AIA) 

The AIA allows businesses to deduct the full value of qualifying capital expenditure from their profits. This is particularly beneficial for businesses planning to invest in new equipment or machinery, as it can significantly reduce their taxable profits. 

Details to highlight:   

Make sure your clients understand that the £1 million AIA limit will continue throughout the 2024/25 tax year. Encourage them to time their investments to fully utilise this allowance, as expenditure exceeding the limit will be subject to the standard capital allowances, which provide less immediate tax relief. 

Capital Gains Tax (CGT) planning 

For 2024/25, the CGT allowance has been significantly reduced. The tax-free allowance for individuals is now £3,000, down from £6,000 in the previous year. For trustees, the allowance is even lower at £1,500. This reduction means that more gains will be subject to tax, increasing the importance of careful planning. 

Details to highlight:   

Advise your clients on strategies to minimise CGT, such as utilising the annual exemption, spreading disposals across tax years, or making use of losses to offset gains. Capium’s tax planning tools can help track and forecast gains, allowing for more effective tax management. 

Maximise Research and Development (R&D) tax relief 

R&D tax relief remains a powerful incentive for businesses engaged in innovation, and the government announced that this year the two core R&D scheme – SME and RDEC – would be merged to keep things simple, with a headline rate of relief of 20%. 

Details to highlight:  

Ensure your clients understand how the new merged scheme differs from the two previous schemes, and that qualifying R&D activities can include work done to overcome scientific or technological uncertainties, even if the project does not succeed. Capium’s software can assist in documenting these activities accurately, making the claims process smoother. 

Plan for pension contributions

The pension annual allowance remains at £60,000 for 2024/25, with a tapered reduction for high earners. Contributions within this limit are deductible from profits, reducing the overall tax liability. However, the pensions lifetime allowance has been abolished and replaced with two new measures. 

Details to highlight:   

Encourage clients to review their pension arrangements regularly, and explain the new ‘lump sum allowance’ and ‘lump sum and death benefit’. Capium’s payroll software integrates pension contributions seamlessly, making it easier for accountants to manage and advise on pension strategies. 

Proper corporation tax planning 

For the 2024/25 tax year, the main rate of corporation tax is 25% for profits over £250,000. Businesses with profits under £50,000 will continue to pay the lower rate of 19%, and those with profits between these thresholds will face a marginal relief rate. 

Details to highlight: 

Help your clients understand that taxable profits include trading profits, investment income, and chargeable gains. Emphasise that allowable business expenses can be deducted from these profits, thus reducing the overall tax liability. 

Missing corporation tax deadlines can result in penalties, so timely management is crucial. 

Use Capium’s tax management tools to track key dates and automate reminders, ensuring your clients never miss a deadline. This also allows for better cash flow planning, helping clients to set aside funds for their tax liabilities. 

The value of accountants in tax planning 

Accountants play a critical role in helping businesses navigate the complexities of tax legislation. Here’s why your role is indispensable: 

• You’re experts in evolving tax laws – the 2024/25 tax year brings several changes to tax rates and allowances, including a reduction in the dividend allowance to £500 and adjustments to income tax thresholds that clients might not be aware of 

• You’re not just compliance officers – you’re strategic advisors who can leverage your knowledge of tax legislation and financial planning to identify opportunities for tax savings and business growth 

• You help mitigate risk – errors in tax filing can lead to costly penalties; you mitigate these risks by ensuring accuracy and compliance. Capium’s software automates many of these processes, reducing the risk of human error and ensuring that all filings are submitted on time. 

As the 2024/25 tax year progresses, effective tax planning will be essential for your clients’ success. By leveraging your expertise and Capium’s advanced software solutions, you can provide the strategic advice that helps businesses not only meet their tax obligations, but thrive in a competitive market.  

The post Top tips for business tax planning in 2024 to share with your clients appeared first on capium.

One of the best things about the fact that our founders are former accountants is that we really understand the challenges accounting firms face on a day-to-day basis. We’ve been there, we get it, and we’re committed to designing software that genuinely makes your lives easier.  

Our Corporation Tax module is something we’re proud of. We’ve designed it to be slick, easy, and effective to use – removing lots of the niggles that come with preparing and submitting returns – and the accountants we speak to regularly tell us what a difference it’s made to their practice’s approach.  

Here are five reasons why accounting firms love our Corporation Tax module.  

1.Time-saving automation is front and centre 

We’ve said it before and we’ll say it again: automation is one of the single, biggest time-saving factors for accountants today – and utilising software that leverages automation properly is key to reaping its rewards.  

From auto-generating corporation tax forms to auto-iXBRL tagging, our Corporation Tax module handles all the tasks involved in filing corporation tax returns – all with minimal intervention from you. That means a speedier process, and less room for error.  

By highlighting potential issues through pre-submission checks, our module lets you focus on higher-value tasks – rather than getting bogged down by manual data entry or corrections. 

2.Seamless integration and real-time collaboration 

We’ve designed our Capium ecosystem carefully, and integration is a key part of what makes it easy to use. Our Corporation Tax module integrates with other modules, like payroll and bookkeeping, meaning workflows are streamlined and financial data is always synchronised.  

And, because our software is cloud-based, it means you can collaborate with colleagues and clients in real-time, regardless of your location. In real terms, that means enhanced productivity and keeping everyone in the loop – meaning better decision-making and happier clients. 

3.Live submission tracking with HMRC 

Accountants often tell us that the live submission tracking feature is one of the most beneficial elements of our Corporation Tax module.  

Being able to see real-time updates from HMRC means you can monitor submissions easily, and keep clients up to date and informed about the status of their return – meaning less chance of follow ups or enquiries. It’s transparent, straightforward, and helps make managing multiple submissions easier to keep track of. 

4.Support for all variations of CT600 forms 

No two corporation tax submissions look alike, which is why we’ve designed our Corporation Tax module to support all variations of the CT600 forms – including full forms, short forms, and those related to Research and Development claims, too.  

It’s a feature we’ve prioritised – because it eliminates the need to switch between different software or manual processes and means you can accommodate your clients’ needs and tailor your service to your whole client-base – all from within a one-stop-shop system.  

5.Compliance and security: future-proofed 

We all know how important future-proofing is when it comes to accounting tech, which is why we’ve designed our software to comply with both existing regulations (MTD and GDPR), as well as to anticipate and respond to upcoming changes.  

We take data security seriously. Our secure cloud-based servers and strict adherence to data protection protocols mean all your clients’ data is handled securely, giving you the peace of mind to focus on delivering high-quality services without worrying about regulatory pitfalls.  

Ready to get started? 

When it comes to Corporation Tax software, our module offers a robust, efficient, and reliable solution for any accounting practice looking to simplify and streamline its approach. With seamless integration, advanced automation, and real-time collaboration, we’re certain our software will help boost efficiency, accuracy, and client satisfaction. And, with our support team on hand to help you if you need us, there’s no reason not to give us a try.  

Book your free trial today. 

The post Five reasons accounting firms love our Corporation Tax module appeared first on capium.