When is corporation tax due?

Understanding when is corporation tax due is one of the most important parts of running a limited company, yet it is something many businesses still get wrong. According to HMRC, late payment interest and penalties continue to contribute to the UK tax gap, which was estimated at £39.8 billion.

Missing Corporation Tax deadlines can quickly create unnecessary costs for businesses through penalties, interest charges, and cash flow disruption. According to HMRC, the UK tax gap is estimated at £39.8 billion, with errors and non-compliance continuing to play a major role.

In this guide, we explain exactly when corporation tax is due, what the payment deadlines mean for your business, and how to stay organised so you can avoid penalties and keep your finances under control.

Understanding Corporation Tax Deadlines for Your Business

Corporation Tax deadlines are based on your company’s accounting period and taxable profits. Your accounting period is usually the financial year covered by your company accounts, although in some cases businesses can have more than one accounting period in a year.

For many business owners, understanding when is corporation tax due comes down to knowing three separate dates. The first is the deadline for filing your accounts with Companies House. The second is the deadline for paying Corporation Tax to HMRC. The third is the deadline for submitting your Corporation Tax return.

These dates are all different, which is where confusion often starts. Many businesses assume they pay Corporation Tax when they file their return, but in reality the payment is usually due earlier. Keeping track of these dates helps businesses manage cash flow more confidently and avoid unnecessary pressure close to deadlines.

Corporation Tax Deadlines for Businesses Earning Up to £1.5 Million

If your company’s taxable profits are below £1.5 million, Corporation Tax is normally due 9 months and 1 day after the end of your accounting period.

For example, if your year end is 31 March, your Corporation Tax payment will usually be due on 1 January the following year.

A common question businesses ask is, “What is the deadline for paying Corporation Tax?” and for most small and medium-sized businesses, this is the answer.

Your Corporation Tax return itself is normally due 12 months after the end of the accounting period. This means there is often a gap between the payment deadline and the return filing deadline. Businesses should prepare their figures early so they know exactly what is owed before the payment becomes due.

Corporation Tax Rules for Businesses Earning Over £1.5 Million

Larger businesses with taxable profits above £1.5 million are usually required to pay Corporation Tax in quarterly instalments instead of one single payment.

Businesses with profits above £20 million may also face earlier instalment deadlines, meaning payments are spread across the accounting period itself rather than being settled after year end.

The aim is to make businesses pay Corporation Tax closer to the point where profits are earned, rather than waiting until after the year end. For businesses, it means cash flow forecasting and financial planning become much more important. If profits increase unexpectedly and businesses are not prepared, these earlier payment deadlines can create pressure.

What Happens If You Miss a Corporation Tax Deadline?

Missing a Corporation Tax deadline can create several problems for businesses. HMRC can charge late filing penalties, apply interest to unpaid tax, and increase compliance checks where businesses repeatedly miss deadlines or submit incorrect information.

Even companies with no Corporation Tax to pay can still receive penalties for filing late. This is why understanding when is corporation tax due matters so much. It is not simply about paying tax. It is about maintaining accurate records, meeting obligations on time, and avoiding unnecessary costs.

Late payments can also affect business planning. Money that could have been used to support growth or day-to-day operations may instead be lost to interest charges and penalties.

Key Business Tax Deadlines Every Company Should Know

Understanding when is corporation tax due is only one part of managing business taxes. Companies also need to stay on top of VAT deadlines, payroll reporting, Self-Assessment obligations, and Companies House filing dates.

Keeping accurate records throughout the year makes these deadlines easier to manage. Businesses that leave bookkeeping until the last minute often struggle to prepare reliable figures, increasing the risk of errors and missed deadlines.

Corporation Tax and Companies House Deadlines Explained

Limited companies usually need to file accounts with Companies House within 9 months of the accounting year end. Corporation Tax payments are generally due 9 months and 1 day after the end of the accounting period, while Corporation Tax returns are due 12 months after the accounting period ends.

Because these deadlines are separate, businesses need to understand which obligations apply and when. Preparing accounts early often gives companies a clearer understanding of their tax position and helps avoid surprises.

Self-Assessment Income Tax Deadlines

Self-employed individuals and partnerships generally submit online tax returns by 31 January each year. Payments on account may also apply, with an additional payment often due by 31 July.

These deadlines can affect directors who receive untaxed income outside payroll, making personal tax planning just as important as company tax planning.

National Insurance Deadlines for Businesses

National Insurance deadlines are usually linked to payroll or Self-Assessment reporting. Employers must calculate and report contributions correctly, while sole traders and partnerships often pay National Insurance through their personal tax return.

Maintaining organised payroll records helps businesses avoid reporting issues and payment mistakes.

PAYE Deadlines and Employer Responsibilities

Businesses operating PAYE must submit payroll information to HMRC on or before employees are paid. PAYE, National Insurance, and CIS payments are usually due by the 19th of the following month for postal payments or the 22nd if paid electronically.

Keeping payroll reporting accurate and on time helps businesses avoid penalties, reduce HMRC attention, and keep payroll running smoothly for employees.

VAT Return and VAT Payment Deadlines

Most VAT-registered businesses submit VAT returns quarterly. VAT returns and payments are normally due 1 month and 7 days after the end of the VAT quarter.

Using Making Tax Digital compatible software helps businesses maintain accurate records and reduces the risk of errors within VAT reporting.

Capital Gains Tax Deadlines Explained

Capital Gains Tax can apply when assets such as shares, investment property, or businesses are sold for a profit. In the case of residential property sales, gains usually need to be reported and paid within 60 days of completion.

Understanding these deadlines helps businesses and individuals avoid penalties and maintain stronger control over tax liabilities.

Simple Ways to Stay on Top of Tax Deadlines

Keeping bookkeeping records updated throughout the year makes managing deadlines far easier. Businesses that regularly review financial information usually have better visibility over upcoming liabilities and fewer last-minute issues.

Using accounting software, setting reminders, and reviewing deadlines monthly helps reduce pressure and improves confidence in financial reporting.

UK Corporation Tax Administration Explained

The UK Corporation Tax system works on a self-assessment basis. This means companies are responsible for calculating, reporting, and paying their own tax liabilities correctly and on time.

Businesses are expected to keep accurate records and submit information digitally, which means bookkeeping and reporting systems need to stay organised throughout the year.

Understanding Your Corporation Tax Accounting Period

Your accounting period is normally the financial year covered by your company accounts. A Corporation Tax accounting period cannot exceed 12 months, even where statutory accounts cover a longer period.

If accounts are prepared for longer than 12 months, businesses may need to submit more than one Corporation Tax return.

How and When to File a Corporation Tax Return

Corporation Tax returns are normally submitted online within 12 months of the end of the accounting period. The return includes the company’s own calculation of the tax due.

This self-assessment system places responsibility on businesses to maintain accurate financial records and submit correct information.

Digital Filing Requirements for UK Businesses

Corporation Tax returns must be filed electronically using HMRC-approved formats. Company accounts submitted alongside the return must also meet digital filing standards.

Digital filing rules are intended to improve reporting accuracy and support more efficient communication with HMRC.

When Corporation Tax Payments Are Due

For most businesses asking “What is the deadline for paying Corporation Tax?”, the answer remains 9 months and 1 day after the accounting period ends.

Larger businesses may need to pay in quarterly instalments instead. Knowing which rules apply to your business helps avoid confusion and improves financial planning.

Corporation Tax Penalties and Compliance Risks

HMRC can issue penalties for late filing, incorrect returns, poor record-keeping, or failure to respond to information requests.

Businesses with disorganised records are more likely to experience reporting errors and compliance problems. Maintaining clear financial systems helps reduce risk and provides greater confidence in reported figures.

Additional Reporting Requirements for Larger Businesses

Some larger companies face extra compliance obligations, including tax strategy reporting and Senior Accounting Officer requirements.

These rules are intended to improve accountability and transparency around tax reporting and governance.

HMRC Tax Enquiries and Audit Processes Explained

HMRC can open enquiries into Corporation Tax returns after submission. These enquiries can range from simple information requests to more detailed technical reviews.

Keeping accurate records and supporting documentation helps businesses respond more confidently if enquiries arise.

Corporate Criminal Offences and Tax Evasion Rules

The UK has legislation targeting businesses that fail to prevent the facilitation of tax evasion. Companies are expected to maintain proper internal controls and reporting procedures.

Failure to comply can lead to financial penalties and reputational damage.

Senior Accounting Officer Rules and Tax Strategy Requirements

Large businesses may be required to appoint a Senior Accounting Officer and publish an annual UK tax strategy.

These requirements focus on maintaining accurate tax accounting arrangements and improving governance within larger organisations.

Reporting Uncertain Tax Treatments to HMRC

Some larger businesses must report uncertain tax treatments where significant amounts of tax are involved.

The aim is to improve transparency and reduce disputes between businesses and HMRC.

HMRC Rules on Tax Avoidance Schemes

Certain tax planning arrangements must be disclosed to HMRC under anti-avoidance legislation.

These reporting rules are designed to reduce aggressive tax avoidance and improve transparency within the tax system.

Corporation Tax Time Limits and HMRC Enquiry Windows

HMRC generally has up to 12 months after a Corporation Tax return is filed to open an enquiry.

Longer time limits may apply where errors, omissions, or inadequate disclosures are identified.

Managing Tax Compliance in Large Businesses

Larger businesses often face more detailed reporting obligations and greater HMRC scrutiny.

Strong financial systems, organised records, and regular reviews help businesses reduce compliance risks and maintain better visibility over their tax position.

When is corporation tax due?: Final thoughts

In conclusion, understanding when is corporation tax due helps businesses stay compliant, avoid penalties, and maintain stronger control over cash flow and financial reporting.

We have covered the main Corporation Tax deadlines, filing requirements, payment methods, and wider compliance responsibilities businesses need to manage throughout the year. While the rules can seem confusing at first, keeping organised records and planning ahead makes managing Corporation Tax far more manageable.

If you would like support understanding your deadlines or managing your business taxes with more confidence, speak to MGRW+ today.