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Key Corporation Tax Dates UK Business Owners Should Know

Stay informed about crucial UK tax year dates for corporations. Learn about deadlines for filing returns, making payments, and avoiding penalties.

arj
Arjun Kumar
Founder
Oct 17, 2025
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A close-up photograph of a printed calendar page with the months "December," "January," and "March" prominently displayed in bold black text.

Understanding and keeping track of important tax dates is critical for any UK-based firm to ensure they are complying with tax legislation and not leaving themselves vulnerable to any fines. Corporation tax is a tax levied on company earnings, and business owners must be aware of key dates for filing tax reports, making payments, and submitting required documents.

Here, we will discuss the essential UK tax year dates for corporations.

UK Tax Year Dates Every Company Should Know

Following are the UK tax year dates important for company owners:

Company Tax Year End Date

In the UK, every company has separate accounting dates based on incorporation date, which can be changed. The deadline for submitting your company's tax return and paying any taxes owed is usually 12 months following the end of the accounting period.

Suppose your company's fiscal year ends on March 31, which aligns with the UK tax year end date. You must complete your tax return and make any necessary payments by March 31 of the following year, according to UK tax year dates.

Payment Deadline

The deadline to pay corporation tax does not align with the deadline for filing your tax return. You should submit your company tax return no later than 12 months after the end of your accounting period, which corresponds to the UK tax year end date.

CT600 Form Submittal Date

The CT600 form is the official corporation tax return form that must be sent to HMRC with your company's financial statements. The deadline for submitting the CT600 form is usually 12 months following the end of your accounting period.

Capital Allowance Claim Deadline

Companies may claim capital allowances on qualified assets to decrease their taxable earnings. The deadline for claiming capital allowances in your tax return is the same as the deadline for submitting the return, which is usually 12 months after the end of your accounting period.

Corporation Tax Payment on Account

In addition to paying corporation tax for the current fiscal year, you may be obliged to make payments on account for the following year. These payments are often due in two instalments, with the first due six months into the current fiscal year and the second due twelve months into the year.

Annual Account Dates

Annual accounts are a reporting requirement based on financial information. Regardless of whether your business is active, you are required to submit annual accounts to Companies House and HMRC each year. If your firm has never conducted any trading, you can file accounts as an inactive company. These accounts must be submitted to Companies House by the specified 'due by' date.

The first set of accounts is due 21 months after the company's incorporation date. Accounts must be submitted within nine months after the accounting reference date for subsequent years.

For example:

On January 8, 2024, you register a firm.

The accounting reference date is set at 31/08/2025.

You should submit the first set of annual accounts no later than January 5, 2026 - the account's due date.

The following accounting reference date is 31/08/2026; The following account due date is 31/5/2027.

UK Tax Year Dates Calendar

Here is the tabular overview of UK tax year dates:

  • 3 months since you started trading: Register for Corporation Tax.

  • 1 year after registration: File a confirmation statement.

  • 21 months after registration: First account filing deadline.

  • 9 months after the end of your business accounting period: Regular accounts filing deadline (except for the first year, which is 21 months).

  • 9 months and 1 day after the end of the business accounting period: Pay Corporation Tax.

  • 12 months after the end of the accounting period: Submit Corporation Tax return.

  • VAT payment date: Due one month and 7 days after the end of each VAT quarter.

  • PAYE payment date: Paid monthly on the 22nd of the next month.

When is the Corporation Tax Deadline?

Please note that the Corporation Tax bill is typically due nine months and one day after your accounting period ends. It's important to be aware that large corporations might need to pay their Corporation Tax in instalments, with certain payments due during the accounting year instead of after it ends. Also, be mindful of the UK tax year start date and end date.

If you do not file your confirmation statement by the required deadline, you will be in violation of the Companies Act 2006. This could result in fines of up to £5,000 for company officials, and the company could be struck off the registry. However, submitting your confirmation statement on time can avoid these consequences.

Bottom Line on UK Tax Year Dates

To keep things organised, it's important that business owners know and follow the key tax dates UK. This helps them pay their taxes on time and avoid penalties. By keeping track of important dates, companies can stay on top of their taxes and manage their finances better. Timely payments and proper document submissions are crucial.

Using Taxd for effective tax planning and meeting these deadlines is key to keeping your finances healthy and ensuring your business thrives in the long run.

FAQs

1: When is my company's corporate tax return due?

The corporate tax return deadline is usually 12 months following the accounting period. You must send the CT600 form, the official corporation return form, to HMRC with your company's financial statements by this date.

2: When must I pay company tax?

Corporation tax must be paid within 9 months and 1 day of your accounting period.

3: What happens if corporations miss the UK tax year start date and end date?

Missing company tax deadlines may result in fines and HMRC investigations. Financial penalties and heightened scrutiny may arise from late tax returns or payments. It's essential to know the consequences of missing deadlines and take proactive steps to satisfy tax requirements.

arj
Arjun Kumar
Founder
Arj is ATT qualified with over 8 years’ experience developing products and propositions, as well as leading global networks of technology teams. He’s a former manager at PwC.

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