Understanding tax returns for companies is essential for every UK director. This article explains deadlines, what to file, what you can claim, and how expert accountants help you avoid penalties and reduce your tax bill.

Tax Returns for Companies: Deadlines, Filing & Advice

This guide from Tax Return Accountants covers everything you need to know about tax returns for companies, so you can stay compliant with confidence.

Company Tax Returns Explained: What Every UK Business Must File

Over 800,000 HMRC late filing penalties were issued to UK companies in 2024/25 alone (source: GOV.UK).

Every UK limited company must submit a detailed annual report to HM Revenue & Customs (HMRC) showing all company income, expenses, and Corporation Tax due for its unique accounting period. This report is called a CT600. Unlike Self Assessment, which is for individuals and landlords, a CT600 is a legal requirement for companies, regardless of whether the business made a profit or loss.

The HMRC company tax submission process requires you to gather your company’s financial records, prepare statutory accounts, calculate your Corporation Tax, and submit the CT600 online. If you run a dormant company (no trading activity), you may still need to file a ‘dormant’ return to HMRC and confirm your status with Companies House. Failing to submit on time triggers automatic penalties and, in severe cases, may lead to company strike-off.

Most directors are surprised to learn that the deadlines for company tax returns are not based on the standard UK tax year (6 April–5 April), but instead on your company’s own accounting year end. This is a common source of confusion and missed deadlines.

Missing your company’s CT600 deadline is one of the most expensive mistakes a director can make.

If you’re unsure about your obligations, our Corporation Tax Service offers full support, from calculating tax to digital HMRC submission.

For further details, see GOV.UK: Company Tax Returns.

What is a CT600 Company Tax Return?

The CT600 is the official HMRC form for reporting your company’s annual profits, losses, and tax calculations. It is the foundation of business tax compliance in the UK.

Who Must File and When?

All active UK limited companies must submit a CT600 for each accounting period, even if no tax is due. Non-UK companies with a UK branch may also have to file.

Key Filing Responsibilities

Directors are legally responsible for ensuring the CT600 is accurate and submitted on time. This includes providing supporting accounts and keeping all records for at least six years.

Company Tax Return Deadlines and Penalties: What You Need to Know

Missing your company tax return deadline results in automatic penalties and interest charges from both HMRC and Companies House.

• Your company’s CT600 must be submitted within 12 months of the end of your accounting period.
• Corporation Tax payment is due 9 months and 1 day after the period ends.
• Annual accounts must be sent to Companies House within 9 months of the accounting year end.
• Confirmation statements must be filed within 14 days of your company’s review period.
• Penalties for late filing start at £100 but can escalate to £1,500 or more.

Understanding these deadlines is vital for avoiding costly fines. Many directors mistakenly believe the deadlines align with the UK tax year, but they are always based on your company’s unique accounting year end.

For example, a Leicester-based small business recently missed its CT600 deadline by four months, resulting in an immediate £100 penalty, followed by a £500 penalty after three months. After moving to Tax Return Accountants, they filed on time the following year and avoided all further fines.

Late payment of Corporation Tax also triggers daily interest and further surcharges. If you are already late, contact an accountant immediately to limit penalties and negotiate with HMRC where possible.

For more details on deadlines, see GOV.UK: File Company Accounts and Tax Return.

How to File Corporation Tax in the UK: Step-by-Step Guide

How do you actually submit your company’s tax return and avoid mistakes?

Using cloud software like Xero, QuickBooks, FreeAgent, or Sage Accounting can dramatically speed up this process. These platforms automate calculations, flag missing data, and integrate with your accountant for direct digital submission. For a worked example: if your accounting year ends 31 March 2026, your CT600 must be submitted by 31 March 2027, and Corporation Tax paid by 1 January 2027.

What most guides fail to mention: If you make a mistake in your CT600, HMRC may open an enquiry within 12 months of submission. This can result in extra tax, interest, and penalties. Having a professional accountant means errors are spotted before submission, reducing enquiry risk.

If you need help, our Bookkeeping Service ensures your records are always ready for submission.

See GOV.UK: File Company Accounts and Tax Return for the official step-by-step process.

Essential Documents Needed

You’ll need your company’s annual accounts, bank statements, UTR, Companies House authentication code, and any prior submissions. If you use payroll or are VAT registered, those records are also required.

Corporation Tax Filing Process

Prepare your accounts, calculate Corporation Tax, complete the CT600, and submit online. Digital tools like Xero and Sage can help you avoid manual errors.

Using Software and Accountants

Most UK companies now use software or professional accountants. This approach reduces mistakes, speeds up the process, and ensures you claim every allowable expense.

What Expenses Can Companies Claim? UK Allowable Deductions Explained

Imagine a freelance designer in Manchester who overlooked claiming software subscriptions and home office expenses. After switching to digital record keeping and working with Tax Return Accountants, they recouped £1,200 in missed deductions and reduced their Corporation Tax bill by £228 the following year.

• Staff costs, salaries, and employer National Insurance
• Office rent, business rates, and utilities
• Equipment, IT hardware, and software subscriptions
• Business travel, mileage, and accommodation (excluding commuting)
• Professional fees (accountants, legal advice, training)
• Industry-specific costs (e.g., tools for construction, medical equipment for healthcare)
• Marketing, advertising, and website expenses
• Insurance premiums, bank charges, and interest on business loans
• Phone, broadband, and stationery
• Charitable donations (if qualifying)

Keeping digital records is crucial. Under Making Tax Digital, HMRC expects companies to retain digital receipts and records. This not only ensures full claims, but also protects you in the event of an HMRC enquiry.

If you’re VAT registered, our VAT Returns Service can help you maximise input VAT claims on allowable expenses.

For more detail, see GOV.UK: Allowable Business Expenses.

Limited Company Tax Obligations: Rates, Advice, and Compliance in

Corporation Tax rates for 2025/26 and 2026/27 are 19% for profits under £50,000 and 25% for profits over £250,000 (source: GOV.UK).

UK limited companies must meet several annual obligations beyond just the CT600. These include sending annual accounts to Companies House, submitting a confirmation statement, and paying the correct amount of Corporation Tax. Failure to comply can result in penalties, HMRC enquiries, and even being struck off the register.

Unlike many guides, we highlight that Making Tax Digital (MTD) for Corporation Tax is not yet mandatory for 2026—but digital record keeping is still strongly recommended. Companies must also keep all records for at least six years, and should be prepared for random HMRC compliance checks.

Staying compliant means more than just meeting deadlines.

• Check your company’s accounting year end and set reminders for all filing deadlines.
• Use digital software for record keeping and submission.
• Claim all allowable expenses—review the full HMRC list annually.
• Submit your annual confirmation statement to Companies House within 14 days of the review period end.
• Keep all supporting documents for at least six years.

Even dormant companies must submit annual accounts and a confirmation statement to Companies House, or risk a strike-off—many directors wrongly believe no filings are needed if there’s no trading.

If you need help, our Limited Company Accountants service covers all annual compliance for a fixed monthly fee.

For the latest rates, see GOV.UK: Corporation Tax Rates.

Small Business Tax Advice UK: Landlords, Freelancers, Contractors & More

Every sector faces unique tax return challenges—specialist accountants ensure you stay compliant and claim all reliefs.

Landlords operating through a company must submit a CT600 and pay Corporation Tax on rental profits. If you own property personally, you need to complete a Self Assessment tax return instead. Many landlords miss out on allowable deductions such as mortgage interest or agency fees, leading to higher tax bills. Our Landlord Accountants service ensures all reliefs are claimed.

Freelancers and contractors face additional complexity, including IR35 risk, allowable expenses, and the need to structure income tax-efficiently. For example, a Birmingham-based contractor recently switched to Tax Return Accountants after an IR35 status review, resulting in a £1,100 tax saving through correct expense claims and salary/dividend planning.

Taxi drivers, healthcare professionals, ecommerce sellers, and construction businesses all have sector-specific costs and risks. For instance, construction firms can claim tools and CIS deductions, while healthcare businesses may claim professional subscriptions and specialist equipment.

Proactive advice saves more than just money—it prevents HMRC disputes and stress.

For HMRC’s official guidance, see GOV.UK: Self Assessment Tax Returns.

Self Assessment for Landlords Explained

If your property is owned personally, you must file a Self Assessment return. Company-owned property requires a CT600 and Corporation Tax payment.

Freelancers and Contractors: Unique Filing Needs

Freelancers and contractors often face IR35 risk and should seek specialist advice to optimise their tax position and avoid costly errors.

Expert Help for Niche Sectors

Different sectors—ecommerce, healthcare, taxi drivers—require tailored strategies to maximise claims and stay compliant.

Choosing Accountancy Software: Xero, QuickBooks, FreeAgent & Sage

What’s the best way to keep your company tax return digital, accurate, and MTD-ready?

• Cloud software ensures you meet digital record keeping and MTD requirements.
• Xero, QuickBooks, FreeAgent, and Sage are all HMRC-recognised and suitable for UK SMEs.
• Software enables collaboration with your accountant—no more emailing spreadsheets.
• Cloud systems offer real-time financial insights, improving business decisions.
• Desktop software may suit larger firms needing advanced customisation.

Here’s how the main platforms compare for UK company tax returns:

All four integrate with Tax Return Accountants for seamless tax return preparation, review, and digital submission. Cloud software is usually more cost-effective and supports remote collaboration, while desktop options may offer more custom reporting for larger companies.

Our Making Tax Digital Service can advise on the best software for your needs.

DIY vs Professional Accountant: Costs, Risks, and Benefits Compared

Imagine a Nottingham-based contractor who tried to handle their own tax return using spreadsheets. They missed a filing deadline and received a £100 penalty, then faced an HMRC query over missing expense evidence. After switching to Tax Return Accountants, all returns were filed on time, and £350 in missed expense claims were recovered.

While DIY filing may seem cheaper, the risk of error, missed reliefs, and HMRC penalties is much higher. Professional accountants not only handle submission but also provide tax planning, compliance checks, and HMRC representation. Typical fees for a company director’s return range from £200–£800+, depending on complexity and location. For a detailed breakdown, see our Accountant Pricing page.

For most companies, the savings and peace of mind from professional support far outweigh the extra cost.

How to Find an Accountant Near You

Looking for an accountant near me? Here’s how to choose the right expert for your company’s tax returns.

Tax Return Accountants offers ICAEW-regulated, AAT-accredited company tax services for clients across the UK, with a strong presence in Leicester, London, Birmingham, Manchester, Nottingham, and the East Midlands.

In Leicester, our main office at 6 Egginton Street, LE5 5BA, supports hundreds of local businesses with company tax compliance and digital accounting. London clients benefit from our remote and in-person consultations, while in Birmingham and Manchester, we offer flexible online and face-to-face services for growing SMEs and contractors. Nottingham and the East Midlands see rapid growth in ecommerce and freelance clients, all supported by our team’s deep sector expertise.

When searching for a local accountant, always check for ICAEW or ACCA regulation. A “chartered accountant near me” should be able to provide a practising certificate, professional indemnity insurance, and clear Google Reviews. For a full verification checklist, see below.

Tax Return Accountants, 6 Egginton Street, Leicester, LE5 5BA, 0116 4030595

For more on verifying accountants, see ICAEW: Find a Chartered Accountant and GOV.UK: Find an Accountant.

5-Step Accountant Selection Process

1. Identify your needs: Company tax, VAT, payroll, sector advice?
2. Shortlist 3 accountants: Compare reviews, specialisms, and location.
3. Verify regulation: ICAEW, ACCA, or AAT credentials.
4. Compare pricing: Request clear, fixed-fee quotes.
5. Book consultation: Assess fit and ask about experience with your industry.

UK Accountancy Statistics

• Over 93,000 chartered accountants in the UK (ICAEW, ACCA, CIMA, AAT)
• 1.5 million+ businesses enrolled in Making Tax Digital
• 800,000+ HMRC late filing penalties issued in 2024/25
• 62% of UK SMEs use an external accountant
• £100–£1,500+ in common penalty ranges for late filings

Why Choose Tax Return Accountants?

• ICAEW regulated
• AAT accredited
• Fixed fees from £7.50/month
• MTD support for digital filing
• Dedicated, UK-based accountant
• Nationwide and Leicester-based service
• Free initial consultation