Let’s be honest: very few people start a business because they’re excited about the prospect of filing a tax return. You started your company because you have a passion, a great product, or a service that people need. But as soon as those first profits start rolling in, a familiar shadow looms over the horizon: Corporation Tax.
At Makes Sense Accountants, we talk to business owners every day who find the UK tax system a bit of a maze. Between changing rates, "marginal relief" (which sounds like something out of a physics textbook), and strict deadlines, it’s easy to feel overwhelmed.
The good news? Corporation Tax doesn’t have to be a headache. With a bit of proactive planning and the right accounting for limited companies, you can stay compliant while keeping as much of your hard-earned money as possible.
In this guide, we’re breaking down everything you need to know for 2026 to ensure your limited company succeeds.
What is Corporation Tax, Anyway?
In the simplest terms, Corporation Tax is the tax you pay on your limited company’s taxable profits. Unlike a sole trader who pays Income Tax on their personal earnings, a limited company is a separate legal entity. It earns its own money, and it pays its own tax.
Your "taxable profit" isn't just your total turnover. It’s your income minus your allowable business expenses and any specific tax reliefs you’re entitled to.
If you’re just starting out, you might want to check out our limited company accounting services to see how we help set up the foundations for a tax-efficient business.
The 2026 Corporation Tax Rates: Which One Do You Pay?
As of March 2026, the UK operates a three-tier system for Corporation Tax. The rate you pay depends entirely on how much profit your company makes.
- The Small Profits Rate (19%): This applies to companies with profits up to £50,000. It’s designed to help smaller businesses and start-ups keep more cash for growth.
- The Main Rate (25%): If your profits exceed £250,000, you pay a flat 25% on everything. The government has committed to capping this at 25% for the foreseeable future, providing some much-needed certainty for larger firms.
- The "Marginal Relief" Zone: This is where things get a bit technical. If your profits fall between £50,001 and £250,000, you pay a rate that is tapered between 19% and 25%.
Understanding Marginal Relief
Think of Marginal Relief as a sliding scale. Instead of jumping straight from 19% to 25% the moment you earn £50,001, the rate gradually increases. It essentially means you pay a slightly higher effective rate on the profits in that middle bracket (roughly 26.5% on the portion over £50k) until you hit the 25% average at the top end.
You don’t need to do the math yourself (we use HMRC-approved software for that!), but it’s vital to forecast where you’ll land. If you’re hovering around the £50,000 mark, even a small increase in profit could push you into a higher tax bracket.
Important Deadlines: Don’t Get Caught Out
One of the biggest traps for new directors is the timing of Corporation Tax. Unlike Self-Assessment, where you often pay and file at the same time, Corporation Tax has two separate deadlines: and the payment deadline actually comes before the filing deadline.
- Deadline to Pay: 9 months and 1 day after the end of your accounting period.
- Deadline to File (CT600): 12 months after the end of your accounting period.
For example, if your company year-end is 31st December, you must pay your tax by 1st October the following year, but you don’t technically have to file your return until 31st December.
Tim’s Tip: Don’t wait until the 12-month mark to file. If you wait until December to do the paperwork, you might realize you owed more than you thought back in October: leading to interest charges and penalties. We always recommend getting your accountancy and tax services sorted as soon as your year ends.
How to Reduce Your Corporation Tax Bill (Legally!)
The goal isn't just to pay your tax; it’s to make sure you aren’t paying a penny more than necessary. This is where proactive corporation tax services really shine. Here are the most effective ways to lower your bill:
1. Claim Every Allowable Expense
If an expense is "wholly and exclusively" for business purposes, it can usually be deducted from your profits. This includes:
- Staff salaries and pension contributions.
- Office rent and utilities.
- Travel and accommodation (for business trips).
- Professional fees (like your friendly accountants at Makes Sense!).
- Marketing and advertising costs.
If you’re worried about what counts, take a look at our post on 7 mistakes you’re making with bookkeeping to ensure your records are squeaky clean.
2. Capital Allowances and "Full Expensing"
When you buy assets for the business: like machinery, vans, or IT equipment: you can’t just deduct the whole cost as a regular expense. Instead, you use Capital Allowances.
- Annual Investment Allowance (AIA): You can claim 100% of the cost of most plant and machinery up to £1,000,000 in the year you buy it.
- Full Expensing: For larger companies, this allows a 100% first-year allowance on qualifying new plant and machinery investments.
Timing is everything here. If you know you need new laptops for the team, buying them just before your year-end rather than just after could significantly reduce your tax bill for the current year.
3. R&D Tax Credits
If your company is innovating: whether you're developing new software, creating a new manufacturing process, or improving a product: you might qualify for Research and Development (R&D) tax relief. This is a huge area for tax savings, but HMRC has tightened the rules recently. Proper documentation is essential.
The "Associated Companies" Rule: A Hidden Trap
If you own more than one company, or if your company is part of a group, the £50,000 and £250,000 thresholds are shared.
For example, if you own two limited companies that are "associated," your 19% tax bracket doesn’t go up to £50,000 for each. Instead, it’s split in half: meaning you start paying higher rates once each company hits just £25,000 in profit.
This is a common area where business owners get caught out, resulting in an unexpected tax bill. Part of our business services involves reviewing your entire structure to make sure these thresholds are accounted for.
Making Tax Digital (MTD) and Reporting
HMRC is moving everything toward a digital-first approach. While MTD for Corporation Tax is still evolving, the reporting obligations for limited companies have never been higher. You are expected to keep digital records and use compatible software.
If you’re also a sole trader or have other income streams, staying on top of MTD requirements is a must to avoid falling foul of the new penalty systems.
Why Professional Help Makes Sense
You could try to navigate the CT600 forms and marginal relief calculations yourself, but why would you? Corporation tax is one of those areas where a good accountant doesn't just cost you money: they save you money.
At Makes Sense Accountants, we don’t just "do the books." We look at the big picture. We help you:
- Forecast your tax liability so there are no nasty surprises in 9 months' time.
- Optimize your director’s salary and dividends to ensure you’re personally tax-efficient as well as corporate tax-efficient.
- Handle all correspondence with HMRC, including dealing with any tax investigations should they arise.
Managing a limited company is a big responsibility, but it’s also a fantastic vehicle for growth and wealth creation. By staying on top of your Corporation Tax, you’re ensuring the long-term health of your business.
Ready to Take the Stress Out of Tax?
Whether you’re a start-up looking for your first set of accounts or an established firm aiming to optimize your tax position, we’re here to help. Our limited company accounting services are designed to give you peace of mind so you can focus on what you do best: running your business.
Want to chat about your company’s tax position? Get in touch with us today. We’d love to help make sense of your numbers!
