Corporation Tax (CT600)

We prepare your Corporation Tax computations and CT600, claim all relevant reliefs and make sure you know how much to pay and when.

Corporation Tax Return Service

Overview

All UK limited companies must file a Corporation Tax Return (form CT600) with HMRC, typically once a year, to report their taxable profits and the amount of corporation tax due. This is a task that requires careful attention to detail: the tax rules often differ from the accounting rules, and there are various allowances and reliefs that can reduce your tax bill if applied correctly.

Our Corporation Tax Return service ensures your company’s tax return is prepared accurately and in line with the latest tax laws. We calculate your corporation tax liability (the amount of tax your company needs to pay on its profits) and fill out the CT600 form along with all supporting schedules. Then we file it online with HMRC on your behalf.

We make sure to claim all legitimate expenses and allowances – we want you to only pay the tax you truly owe, and not a penny more. With the corporation tax rate having changed recently (as of 2023/24, it’s 25% for companies with higher profits, whereas small companies up to £50k profits still pay 19%[5]), it’s more important than ever to have an expert ensure you’re calculating things correctly. We’ll also keep you informed of how much and when to pay, so you stay penalty-free.

Benefits

Accurate Tax Calculation:
We take your financial data and compute the taxable profit meticulously, adjusting for all those tricky tax rules (like adding back disallowed expenses, subtracting allowable deductions, and applying reliefs). This accuracy means you won’t overpay tax due to missed deductions, and you won’t underpay and risk HMRC interest or penalties. We cross-verify numbers to ensure everything in the tax return matches your accounts and records, giving you confidence that the return is correct.
Maximize Tax Reliefs & Allowances:
UK tax law provides various ways to legitimately reduce your company’s tax bill – if you know about them. We make sure to utilize all applicable reliefs for you. For example, we’ll apply the Annual Investment Allowance (100% tax write-off on qualifying asset purchases, up to £1 million)[6], claim R&D tax credits if you do innovative projects, use the super-deduction (if still available for your timeline) for equipment investment, etc.

We also consider things like loss relief (if you had a loss, carrying it forward or back) and marginal relief for companies whose profits fall between the small and large thresholds[5]. In short, we don’t just fill a form – we look for opportunities to save you money within what the law allows.
Deadline Management – No Missed Filings:
A corporation tax return is usually due 12 months after the end of your accounting period (financial year) – but remember, the tax payment is due 9 months and 1 day after the year-end[7]. We keep track of both. By engaging us, you essentially transfer that deadline worry to us.

We aim to have your tax return drafted and approved well before the final due date. This not only keeps you compliant with HMRC, avoiding late filing penalties (which start at £100 for missing the deadline), but also gives you more notice of your tax bill so you can manage cash flow for the payment.
HMRC Compliance & Representation:
We prepare the CT600 and accompanying computations in the precise format HMRC requires, using professional tax software that validates everything before submission. Should HMRC have any follow-up questions about your return, we can handle those on your behalf.

As your tax agents, we’re authorized to speak to HMRC for you, which can be a big relief if you’ve ever tried calling them yourself. In the unlikely event of a corporation tax investigation or query, we already have a deep understanding of your numbers and can provide the answers or documentation needed. Basically, we stand between you and the taxman, making the process smooth and professional.
Strategic Tax Planning Insights:
While working on your corporation tax, we also think ahead. We might notice, for instance, that your profit is nearing the threshold where the tax rate jumps from 19% to 25%. We would then discuss planning moves, like perhaps bringing forward some investment (buying equipment, etc.) to utilize allowances and keep profits in the lower band, or other legitimate strategies.

Our service isn’t just backward-looking (filing a return for last year) – we also give proactive advice to optimize for the current and future years. This could include how to extract profit tax-efficiently (salary vs dividends balance), whether to make pension contributions, and so on, tailored to your situation.

Process

Gathering Information:
We start by collecting the financial information needed for the tax return. If we’ve prepared your annual accounts, we already have the base figures (profit before tax, etc.). If not, we’ll ask for your final accounts or profit/loss report for the year, plus details on certain transactions that often have tax implications.

For example, we’ll inquire about any large asset purchases (to claim capital allowances), any entertaining expenses (which aren’t tax-deductible), donations, R&D expenditures, etc. We also check if there are prior year losses or any special claims to consider. Essentially, we create a tax-adjusted view of your profit by identifying where accounting rules and tax rules differ.
Tax Computation:
Using the information, we prepare a corporation tax computation. This is a document that starts with your accounting profit and then makes adjustments to arrive at the taxable profit.

Common adjustments include: adding back expenses that HMRC doesn’t allow (e.g. business entertaining or fines), subtracting things like capital allowances for equipment (instead of accounting depreciation), and incorporating any reliefs (like R&D credits or loss relief).

We calculate the tax due on this taxable profit. As of the current rules, that might involve a split rate: 19% on a portion and 25% on the rest if your profits are above £50k (we apply marginal relief correctly if profits are between £50k and £250k[5]). Don’t worry – we handle all those calculations precisely. The computation will clearly show how we got from profit to tax, which we’ll share with you for transparency.
Preparation of Form CT600:
Once the numbers are finalized, we fill in the CT600 form – this is the official Corporation Tax Return form. It includes your company details, the calculated tax payable, and answers to various questions (like are you claiming any reliefs, do you have associated companies that affect the tax rates, etc.).

We attach the detailed computations and also attach a copy of the accounts in iXBRL format (a special computer-readable format HMRC requires – our software handles the conversion of your accounts to this format). We’ll double-check all the entries to ensure nothing is missed. If there are any supplementary pages needed (for example, if claiming an R&D tax credit or declaring loans to directors, etc.), we complete those schedules as well.
Review & Client Approval:
Accuracy and understanding are important, so before we submit anything, we present you with the draft Corporation Tax Return and the tax computation for review. We will explain in plain language the key points. For instance:

“Your accounting profit was £80,000, but after tax adjustments your taxable profit is £70,000, mainly because we deducted capital allowances on the new van purchase and some entertaining expenses were disallowed. The tax comes out to £13,300.”

We’ll highlight any significant items. If you have questions (“Why is this expense disallowed?” or “Could we use last year’s loss to reduce this year’s tax?” etc.), we answer them and adjust if needed. We want you to be comfortable and agree that the return is true and complete. Once you’re happy, you give us the go-ahead to file.
Filing with HMRC:
We submit the CT600 and all attachments electronically to HMRC through our agent portal. We typically get an immediate confirmation that the submission has been received and, shortly after, an acceptance from HMRC (assuming all is in order, which it should be).

We’ll forward you the confirmation for your records. This filing is usually done well ahead of the 12-month deadline – often we align it with the accounts filing.

Now, even though the return might be filed, remember that the actual tax payment is due by the 9-month + 1 day deadline. For example, if your year-end was 31 March, payment is due by 1 January the following year (regardless of the return being due 31 March). We will have already informed you of the amount due, but we’ll send a formal reminder before the payment deadline, including instructions on how to pay (bank details for HMRC, reference to use, etc.). If you prefer, we can assist you in setting up a direct debit for HMRC corporation tax payment to make it automatic.
Aftercare and Tax Planning:
Our job doesn’t end at filing. We monitor that HMRC processes the return and that your company’s online tax account reflects the submission and the liabilities correctly. If any issues arise (for instance, HMRC raises a query or adjusts something), we address it immediately.

We also take this moment to discuss any tax planning opportunities for the next year. Maybe we note that you’re close to the next tax bracket or perhaps you have unused allowances. We’ll give recommendations – for instance:
- “Next year, if you’re considering buying that machine, do it before year-end to leverage the Annual Investment Allowance.”
- “Maybe make pension contributions to utilize some of the profits and get a deduction.”
Our goal is to be a year-round tax partner, not just a once-a-year form-filler. By being proactive, we help optimize your tax position and avoid surprises.

FAQs

When do I need to file and pay my company’s corporation tax?

A: The filing deadline for the Corporation Tax Return (CT600) is 12 months after the end of your company’s accounting period (usually, that aligns with your financial year)[7]. So if your financial year ends on 31 December 2024, the CT600 must be filed by 31 December 2025.

However, the payment deadline for the corporation tax is 9 months and 1 day after the year-end[7]. In the same example, if year-end is 31 Dec 2024, the tax payment is due by 1 October 2025.

It’s important to note these separate deadlines: you pay first, file later. (Large companies with very big profits have to pay in quarterly installments, but most small businesses don’t need to worry about that.)

We ensure your return is filed on time and will remind you of the payment deadline. In fact, we aim to complete your return well before the 9-month mark, so you actually know what the tax is and can pay it by the deadline. If you pay late, HMRC will charge interest, and if you file late, there are penalties (starting at £100). Our service exists to prevent both from happening.

My company didn’t make a profit (or made a loss). Do I still need to file a corporation tax return?

A: Yes, you do. Every active company must file a Corporation Tax Return regardless of profit level – even if it’s a zero or a loss.

If your company made a loss, filing the return is actually beneficial because you’ll be documenting that loss which can be carried forward to offset future profits (or carried back to the previous year to get a refund, if conditions allow). If you truly had no transactions (dormant company), you might not need a return, but you’d have informed HMRC of dormancy.

For most cases, you still file to show HMRC your position. We will prepare the return accordingly: if it’s a loss, the CT600 will show no tax due and we’ll include a claim to carry the loss forward. It’s important to do that properly to preserve the tax benefit of the loss. So even in a no-profit year, our service ensures your obligations are met and sets you up to save tax in the future when you return to profit.

What kinds of expenses are disallowed in the tax computation?

A: There are several common expenses that HMRC does not allow for corporation tax purposes, even if they’re recorded in your accounts. Examples include:

Business entertainment (taking clients out to dinner – it’s fine as a business expense in your accounts, but not deductible for tax).
Fines and penalties (like parking fines).
Certain donations or gifts that don’t meet HMRC’s criteria.

If your company accounts include depreciation of assets, we replace that with capital allowances in the tax computation, because depreciation isn’t tax-deductible but capital allowances are (often 100% of the asset’s cost under the Annual Investment Allowance[6]).

Another example: if you have provisions in your accounts (like an expected bad debt), sometimes those aren’t allowed until the debt is actually bad.

Don’t worry about remembering all this – our team knows the rules and will adjust your profit accordingly. We’ll also explain any major adjustments to you in the tax computation, so you’re not left wondering why your taxable profit is different from your accounting profit.

Can you help reduce my corporation tax legally?

A: Certainly – our goal is to make sure you take advantage of all legal means to reduce your tax. This includes:

Claiming all eligible expenses:
We ensure you haven’t missed any business expenses that could be claimed. Many owners forget things like use of home office, mileage, or incidental costs – we’ll prompt you so those get included.
Capital allowances:
If you bought assets like equipment, machinery, computers, vehicles, etc., we’ll claim the maximum capital allowances (like the Annual Investment Allowance, which can often deduct 100% of the asset cost up to £1,000,000[6], or special first-year allowances). This can significantly reduce taxable profit.
Reliefs:
We evaluate any special reliefs. For example, if your company does qualifying R&D, you could get extra deductions or a tax credit. If you’re in creative industries, there are specific credits. We’ll discuss your activities to see if any apply.
Loss utilization:
If you have losses from a previous period, we’ll offset them so you pay less tax in the profitable periods.
Optimal remuneration planning:
While this goes a bit beyond just the tax return, we can advise on the mix of salary and dividends for owner-managed businesses to ensure you’re operating tax-efficiently overall.

Rest assured, we won’t do anything aggressive or outside the law – just smart tax planning. We want you to keep as much of your hard-earned profit as possible, while staying fully compliant.

HMRC has sent my company a notice or query about corporation tax – will you deal with it?

A: Yes, if we are your tax agents, we will handle any correspondence from HMRC regarding corporation tax. Often, HMRC might send a notice to file (which we already plan to do) or a statement of account.

If there’s a specific query – for example, asking for clarification on a figure in the return or announcing a compliance check – we will take charge of communications. We’ll inform you of the query and our planned response, gather any additional info from you if needed, and then respond to HMRC in a professional and timely manner.

Having us as a buffer can reduce a lot of stress, because we speak their language and understand what they’re asking for. In most cases, because we prepare returns carefully, queries are rare. But if something comes up, we’re on it.

Also, if any amendments need to be made to a return (say you discovered new information after filing), we can process those amendments with HMRC too.