Every business tax deadline in the UK 2025/2026

We get it. Tax is not many people’s favourite subject! Many business owners (new and experienced) find taxes a bit stressful. But the secret is staying calm and getting organised. 

Running a limited company means juggling two main tax deadlines: personal tax (your salary and dividends) and company tax (corporation tax deadline and annual accounts). Staying on the right side of HMRC means hitting both sets of tax deadlines.

Once you know when the tax return deadlines are for each type of tax you pay, and how the deadlines all slot together, sorting your taxes will be a whole lot easier. We promise! 

So, here’s your essential guide to all the business and tax return deadlines that you’ll want to keep in mind for the 2025/2026 tax year. Got your calendar handy? Good, let’s do this.

In this article:

• 6 April 2025: First day of the 2025/2026 tax year
• 31 July 2025: Second payment on account due (POA)
• 5 October 2025: Register for Self-Assessment 
• 31 October 2025: Paper Self-Assessment returns due
• 30 December 2025: Opt into PAYE
• 31 January 2026: Online tax returns and first payment on account due 
• 19th/22nd monthly: PAYE/NI payments to HMRC
• 5 April 2026: End of the 2025/2026 tax year 
• Corporation Tax
• Annual accounts filing

This date isn’t a deadline for filing or payment, but it defines the start of the UK’s new tax year.

• What you need to do: All income, expenses, or capital gains that occur from this day forward until 5 April 2026 will be included in the Self-Assessment return you file in January 2027
• Plus: You can file your 2023/2024 tax return from this date

This is a deadline for Self-Assessment tax, aka your personal income tax. Payment on account is split into two, due in January and July, based on the previous year’s tax bill.

• Tax/filing type: Personal Income Tax and Class 4 NICs (via Self Assessment)
• What you need to do: You must make your second payment on account (POA) for the 2024/2025 tax year by midnight. 
• Why it’s important: This helps spread your individual tax costs throughout the year. If you anticipate less personal income for 2025/26, you can apply to HMRC to reduce your payment on account

This is one of the trickiest parts of the UK tax system because the payments for previous tax years overlap. But once you understand where the overlaps are, it’s much easier to handle.

This date applies to individuals who need to register for Self-Assessment for the first time, like new directors or sole traders.

• Tax/filing type: Personal Income Tax (Self Assessment)
• What you have to do: If you became a director or started receiving dividends in the 2024/25 tax year (6 April 2024 to 5 April 2025) and have not registered for Self-Assessment before, you must register by this date
• Why it’s important: Missing this date means you risk a penalty for late registration. You must register online to get your Unique Taxpayer Reference (UTR) in time to file your Self-Assessment return by 31 January

If you’ve missed this deadline, it’s a good idea to register as soon as possible to avoid any potential fines from HMRC.

If you choose to file your Self-Assessment return by paper (ie. not online), this is the deadline you need to keep in mind. 

• Tax/filing type: Personal Income Tax (Self-Assessment).
• Why it’s important: We recognise that some people prefer paper forms,  but we (and HMRC) generally advise filing online. Filing online extends your UK tax return deadline by three months (to 31 January 2026). And this way, HMRC can calculate your tax instantly
• What you need to do: If paper filing, you need to send your 2024/2025 Self-Assessment tax return to HMRC by this date

Tip: If you do miss this deadline, don’t panic. You still have time to meet the online tax return deadline. Importantly: just don’t file both!

Opting into PAYE lets you manage how you pay any tax owed for the 2024/2025 tax year by spreading the cost, which could be great news for your cash flow. But it does come with eligibility requirements. 

• Tax/filing type: Personal Income Tax (Self-Assessment)
• What you need to do: You must file your 2024/2025 tax return online by this date, and the outstanding tax owed must be less than £3,000. Then, you can opt in to have HMRC collect the tax over the course of the next tax year 
• Why it’s important: Instead of paying the lump sum on 31 January 2026, tax is collected gradually through your payroll (via your PAYE tax code) over the subsequent tax year (starting 6 April 2026)

This is the main online tax return deadline in the UK. HMRC must receive your online tax return by midnight tonight or you could get a fine. 

• Tax/filing type: Personal Income Tax and Capital Gains Tax (Self-Assessment)
• Why it’s important: This is three deadlines in one! If you’re late, you’ll receive an automatic £100 penalty, plus late payment interest
• What you have to do: 

1. Meet the Self-Assessment tax return filing deadline: Submit your personal Self-Assessment tax return (but preferably do it before this deadline!), covering all salary and dividends received in the 2024/25 tax year

2. Final Payment: Pay the balance for any tax you owe for the 2024/2025 tax year

3: First POA: Pay the first payment on account (POA) towards your estimated tax bill for the 2025/2026 tax year

For limited companies, the company is responsible for deducting PAYE/NI and paying it to HMRC on the employee’s behalf — typically on a monthly or quarterly basis.

As a limited company owner or director, you are responsible for making sure these payments are submitted on time.

• Tax/filing type: PAYE and both employee and employer National Insurance Contributions (NICs)
• What you have to do: You must report PAYE and NI deductions to HMRC in real time, which involves sending a Full Payment Submission (FPD) on or before each payday. Then, the total amount owed (PAYE and NI) must then be paid by:

• 19th of the month: If paying by cheque
• 22nd of the month: If paying online or by bank transfer
• Why it’s important: This is how the company correctly handles the tax on employee salaries. Missing this deadline results in interest and potential penalties for the company.
  
  

All good things must come to an end, right? Like 6 April, this isn’t a payment date but an important milestone to keep in mind.

• Tax/filing type: Marks the end of the UK’s tax year
• What you have to do: All the income earned up to this date must be reported on your Self-Assessment tax return — now due in January 2027
• Why it’s important: This is the last chance to do tax-saving activities, like making pension contributions or using ISA allowances for the current tax year

Your limited company must pay tax on its profits — this is called corporation tax. 

In the UK, corporation tax returns are based on your company’s unique accounting year-end date. There are two separate, but connected, deadlines: the payment due date and the filing deadline. 

Let’s look at these two corporation tax filing deadlines in more detail:

1. The payment deadline (the money)

• Tax/filing type: Corporation tax payment
• What you need to do: Your company must pay its corporation tax bill 9 months and 1 day after the end of its 12-month accounting period
• Why it’s important: The money is due before the paperwork (Form CT600) is officially filed, so you must make sure there’s enough funds in your business account to meet this payment well in advance

2. The filing deadline (the paperwork)

• Tax/filing type: Corporation tax return Filing (Form CT600)
• What you need to do: The final deadline for filing your company tax return (Form CT600) with HMRC is 12 months after the end of the accounting period
• Why it’s important: This submission officially closes your company’s tax period with HMRC

Example: If your company’s year-end is 31 December 2025, your payment is due 1 October 2026, but your CT600 filing is due 31 December 2026.

This probably feels like a backwards process, but there’s a logical reason for it — and it’s related to your company’s annual accounts, which we look at below in more detail.

Every company has a legal (“statutory”) responsibility to file annual accounts to Companies House. This is completely separate from the tax filing process with HMRC. 

It probably does seem like a tax deadline, but the profit figure on your company’s annual accounts is what’s used to calculate your corporation tax bill. 

• Tax/filing type: Annual accounts filing with Companies House
• What you need to do: You must file your company’s annual accounts with Companies House within 9 months of the company’s accounting year-end date 
• Why it’s important: Annual accounts are your company’s official financial reports. They show how your company is performing over a one-year timeframe — and therefore provide a clear picture of your company’s financial health to stakeholders, like investors and shareholders. 

It’s worth noting that your limited company’s annual accounts are public. They are available to anyone who searches for them on the Companies House register.

First of all, if you’ve missed an HMRC tax deadline, don’t panic. Dealing with tax penalties can be stressful, but they can be avoided with good organisation and planning. 

HMRC penalties are automatic and can be quite expensive — so knowing the risks is key.

Delay	Penalty type	Penalty amount
1 day	Automatic flat penalty	£100 fine instantly applied on 1 February
Over 3 months	Daily penalties begin	£10 per day for up to 90 days (max £900)
Over 6 months	Tax-based penalty	5% of tax due (or £300, whichever is greater)
Over 12 months	Further tax-based penalty	Another 5% of tax due (or £300, whichever is greater)

Late payment: Self-Assessment penalties (limited companies & sole traders)

If you are late paying your tax bill, you’ll receive penalties of 5% of your unpaid tax bill at: 

• 30 days 
• 6 months 
• 12 months 

HMRC will also charge interest on the amount you owe. Remember, you need to file and pay before 31 January. 

Limited company penalties

Limited companies get two sets of automatic penalties for late filing, depending on which government body the documents were due to (HMRC or Companies House).

1. Penalties for late annual accounts (Companies House)

If you don’t meet your Companies House annual accounts filing deadline (9 months after year-end), your company will directly receive the below penalties, which are doubled if the company files late two years in a row.

Delay	Penalty amount
Up to 1 Month	£150
1 to 3 Months	£375
3 to 6 Months	£750
Over 6 Months	£1,500

2.  Penalties for late CT600 filing (HMRC)

To recap, this penalty applies to your company’s formal tax return (CT600), which is due 12 months after the end of your accounting period.

Delay	Penalty
1 day	£100 automatic flat penalty
Over 3 months late	A further £100 flat penalty
Over 6 months late	HMRC estimates your Corporation Tax and charges a penalty of 10% of the tax due.
Over 12 months late	An additional penalty of 10% of the tax due.

With careful planning, you should be able to avoid penalties — and it’s always worth checking the official company tax penalties information, which includes details on how to appeal a fine.

Yes, HMRC does send reminders for upcoming payments or notifications if you’ve missed a tax return deadline. You’ll usually receive official letters or messages in your online HMRC account.

But you should never just rely on these. Think of HMRC’s notices as a courtesy — not your only way of remembering your tax return deadlines. As a limited company director, you are legally responsible for staying on top of the dates yourself. You’ll feel much more confident if you’re in control of your deadlines.

Watch out: HMRC will never send you emails to tell you about tax rebates or penalties, ask you to make payments directly, or threaten legal action. If you’re worried, it’s a good idea to check if an email you’ve received from HMRC is genuine. 

Understanding the difference between these two tax years is really important as it answers the question: “When is the tax return deadline?” for each type of tax:

• Personal tax year: This is fixed and runs from 6 April to 5 April. All your personal income, including salary and dividends from your company, is accounted for within this window and is reported via Self-Assessment
• Business tax year (company accounting period): This starts the day your company is formed (during company registration). It typically ends on the last day of the month in which your 12-month formation anniversary falls 

It’s easy to mix them up! Just remember: April 5th is your personal calendar, and your company has its own unique calendar. 

Submitting your tax return is a legal requirement — every company and sole trader has to do it. It’s a straightforward process if your records are in order.

• Limited companies: You can file the return and accounts together using commercial accounting software, or file them separately using the HMRC online service (for the CT600) and the Companies House online service (for the annual accounts)
• Sole traders: You’ll use HMRC’s Self-Assessment form, which is available both online and via paper 

When you’re running a business, you’re juggling many different things. But it’s super important to keep on top of your tax return deadlines.

The best way to stay ahead of tax is to use a reliable tool, like Countingup’s business current account app, to help you track and categorise your company’s transactions.

Our app can help you with tax, financial reporting, and bookkeeping — but if you need a little more expert advice in the meantime, remember you can always visit our resource hub. It’s full of helpful guides and articles that’ll keep you on the right side of those deadlines. 

Best of luck. You’ve got this!

Yes, absolutely! Filing online is strongly recommended. It gives you an extra three months, pushing your deadline for income tax return from 31 October (for paper returns) to the critical 31 January date. It also allows HMRC to instantly calculate your tax liability and any payments on account (POA).

The official corporation tax deadline for filing the CT600 form with HMRC is 12 months after the company’s accounting period ends. However, the payment of the Corporation Tax owed is due three months earlier, at 9 months and 1 day after the company’s year-end.

The tax return deadline for filing your personal Self Assessment is 31 January following the end of the tax year you are reporting on. For example, income earned in the tax year ending 5 April 2026 must be filed online by 31 January 2027.

Your limited company might be due a tax rebate if it has overpaid Corporation Tax, for instance, due to errors, or if it has made losses that can be carried back to offset profits. Your accountant can assess this as part of your year-end procedures — or you can check with HMRC.

It depends on the complexity of your company’s finances and the organisation of your records. With reliable accounting software and good bookkeeping, the process can be quick. However, preparing the official accounts that accompany the return, often done by an accountant, requires good bookkeeping throughout the year.