Corporation Tax & CT600 Returns for Limited Companies

If you run a limited company, you’ll pay corporation tax on your profits, and you’re legally required to file a company tax return (the CT600) with HMRC every year. At BAA Group, we handle the whole process: we calculate your liability accurately, claim every relief and allowance you’re entitled to, and file your CT600 on time, so your bill is as low as legitimately possible and HMRC stays happy.

Founded by Ben Brophy ACA, we bring over a decade of experience and a jargon-free approach. Corporation tax can feel like a maze of rates, thresholds, and reliefs, we make it simple and make sure you never overpay.

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Corporation tax is calculated from the profit in your annual accounts, which is why we usually prepare both together.

What Is Corporation Tax?

Corporation tax is the tax a limited company pays on its taxable profits, that’s your income minus allowable business expenses, capital allowances, and any reliefs. Unlike income tax, which individuals pay, corporation tax is paid by the company itself.

Every UK limited company that makes a profit must:

Register for corporation tax with HMRC (usually within 3 months of starting to trade)
Keep accurate records of income and expenses
Calculate what’s owed and pay it on time
File a CT600 company tax return with HMRC each year

Get any of these wrong and you risk penalties and interest. We take the lot off your plate.

Corporation Tax Rates for 2026

The amount your company pays depends on its level of profit. These rates have applied since April 2023 and remain unchanged for the 2026 financial year:

19% – the small profits rate, on taxable profits up to £50,000
25% – the main rate, on taxable profits above £250,000
Marginal relief for profits between £50,000 and £250,000, which tapers the effective rate smoothly between 19% and 25%

A word of warning on that middle band: because marginal relief is gradually withdrawn, each extra pound of profit between the thresholds is effectively taxed at around 26.5% — higher than the headline main rate. This is exactly where good planning around timing of income, expenses, and pension contributions can make a real difference. We’ll keep an eye on where your profits sit and advise accordingly.

Important for groups and multiple companies: the £50,000 and £250,000 thresholds are shared between “associated companies.” If you control more than one company, the thresholds are divided between them, which can push each one into a higher rate sooner. We’ll make sure this is handled correctly.

What Is a CT600?

The CT600 is your company tax return, the form you file with HMRC that reports your income, deducts your expenses and reliefs, and calculates the corporation tax you owe. It’s submitted alongside your annual accounts and a corporation tax computation.

We prepare and file your CT600 in full, making sure:

Every allowable expense is captured
All available reliefs and allowances are claimed (capital allowances, R&D relief where relevant, loss relief, and more)
Your figures are consistent with your annual accounts
It’s filed correctly and on time, online

Corporation Tax Deadlines

Corporation tax has a quirk that catches a lot of directors out: you pay the tax before you file the return.

Payment is due 9 months and 1 day after the end of your accounting period. For example, a 31 March year end means payment by 1 January.
Your CT600 return is due 12 months after the end of your accounting period.

Larger companies (profits over £1.5 million) pay in quarterly instalments instead. Late filing brings automatic penalties starting at £100, and interest builds on tax paid late. We track every date so you’re always paid up and filed on time.

Reliefs & Allowances That Could Cut Your Bill

Many companies pay more corporation tax than they need to, simply because reliefs go unclaimed. We look for every legitimate opportunity, including:

Capital allowances on equipment, machinery, and qualifying assets
R&D tax relief for companies doing qualifying development work
Allowable expenses that are often missed
Loss relief, carrying losses back or forward to reduce tax
Pension contributions and director remuneration planning

Note: the main writing-down allowance for capital allowances reduced to 14% from April 2026, so timing of asset purchases matters more than ever. We’ll advise on the best approach for your company.

Why Choose BAA Group for Corporation Tax?

Lower bills, legitimately. We claim every relief and allowance you’re entitled to.
Always on time. We track both your payment and filing deadlines.
Joined-up. We prepare your accounts and CT600 together, so nothing falls through the cracks.
Jargon-free. We explain your tax position in plain English.
Proactive planning. We watch your profit thresholds and advise before year end, not after.
Cloud-powered. Xero, QuickBooks, and FreeAgent keep your records accurate and live.

How It Works

Free consultation. We get to know your company and its tax position.
We gather your figures. From your cloud software or records.
We calculate and optimise. Accurate corporation tax, with every relief claimed.
You approve, we file. We submit your CT600 to HMRC and confirm your payment deadline.
We plan ahead. We flag planning opportunities before your next year end.

Frequently Asked Questions

What’s the corporation tax rate for 2026?

19% on profits up to £50,000, 25% on profits over £250,000, with marginal relief tapering the effective rate in between. These rates are unchanged for the 2026 financial year.

When do I pay corporation tax?

Payment is due 9 months and 1 day after your accounting period ends, which is actually before your CT600 return deadline of 12 months. We make sure you’re ready for both.

What’s the difference between corporation tax and a CT600?

Corporation tax is the tax itself, on your company’s profits. The CT600 is the return you file with HMRC to report those profits and calculate the tax. We handle both.

Do I have to file a CT600 if my company made a loss?

Generally yes HMRC still expects a return even if no tax is due, and filing a loss can be valuable as it may reduce tax in other years. We’ll handle it and put any loss relief to good use.

Can you take over my corporation tax from another accountant?

Absolutely. The handover is straightforward and we’ll manage it for you.

Ready to Take Corporation Tax Off Your Plate?

Let’s get your CT600 filed accurately and on time, with every relief claimed and your bill kept as low as the rules allow.

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