UK Business Tax Deadlines Explained: Key Dates Small Business Owners Must Know

Keeping on top of your tax and reporting obligations are crucial responsibilities for the self-employed and small business owners, and a key part of that is knowing all your tax deadlines, understanding what’s required and preparing accordingly.

Staying organised with your record-keeping, setting reminders for key filing and payment dates, and reviewing your figures regularly all make it far easier to meet your obligations with confidence. Rather than reacting to deadlines as they approach, managing things proactively means you have time to check your numbers, seek advice if needed and ensure everything is submitted correctly and on time.

Missing key dates can result in non-compliance and HMRC attention, investigations, penalties, interest charges and a lot of wasted time, not to mention money, that could have been better spent focused on business growth.

Understanding the tax calendar and your responsibilities, as well as meeting them, helps you create a stable foundation from which your business can grow.

Self-Assessment Tax Returns

If you are self‑employed, a limited company director that’s received an income or dividends, a partner in a partnership or have received untaxed income, you must file an annual Self-Assessment tax return.

The Key Self-Assessment dates are:

• 6^th April – 5^th April – The tax year
• 5^th October – Register for Self-Assessment if you’ve become self-employed
• 31^st October – Deadline for filing paper tax returns
• 31^st January – Deadline for filing online tax returns
• 31^st January – Deadline to pay any tax owed for that same year, including the first payment on account
• 31^st July – Deadline to settle the second payment on account (if applicable)

Payments on account are advance payments towards your next year’s tax bill if your previous year’s tax bill exceeded £1,000. Although this only applies if less than 80% of your income was taxed at source, and is intended to help spread the tax burden across the year rather than paying it all in January.

Making Tax Digital for Income Tax

In time, the traditional Self-Assessment process will be replaced by Making Tax Digital for Income Tax which marks a significant change in how self‑employed people report their tax. MTD mandates that records are stored digitally and the annual Self-Assessment will be superseded by quarterly updates, an End of Period Statement (EOPS) and Final Declaration, all done with HMRC approved software such as FreeAgent or Xero.

The implementation of MTD is a huge undertaking for HMRC so it’s being rolled out in stages. MTD for VAT is already in effect and MTD for Income Tax is next up, with sole traders and unincorporated landlords the first to be affected:

• 6^th April 2026 – MTD for ITSA becomes mandatory for sole traders and unincorporated landlords with an income over £50,000
• 6^th April 2027 – The threshold reduces to £30,000
• 6^th April 2028 – The threshold reduces to £20,000

Eventually all non-PAYE taxpayers will have to comply and it pays to get ahead now and switch to digital to start benefiting sooner, especially if you fall into the above categories.

The filing dates for the quarterly updates are:

• 7^th August – Q1 update (6^th Apr – 5^th Jul)
• 7^th November – Q2 update (6^th Jul – 5^th Oct)
• 7^th February – Q3 update (6^th Oct – 5^th Jan)
• 7^th May – Q4 update (6^th Jan – 5^th Apr)

Your End of Period Statement (EOPS) to finalise business income and expenses, and your Final Declaration (to confirm all other income and to finalise your overall tax position) both need to be filed by 31^st January following the end of the tax year.

VAT Returns

If your VAT-taxable turnover hits the mandatory registration threshold of £90,000 in a rolling 12 month period, you must register for VAT within 30 days of the end of the month in which the threshold was triggered.

You must also register if you expect to exceed the threshold within the next 30 days, by the end of that 30-day period. Failure to register on time could mean you’re subjected to penalties and backdated VAT being owed. Key dates regarding VAT vary depending on which scheme you are registered for.

Standard VAT Accounting Scheme

• VAT Return Deadline – Due 1 month and 7 days after the end of the VAT period
• VAT Payment Deadline – 1 month and 7 days after the VAT period ends

Annual Accounting Scheme

• VAT Return Deadline – Due 2 months after the end of the 12-month accounting period
• VAT Payment Deadline – Payments are made in advance throughout the year, either 9 monthly or 3 quarterly instalments followed by a balancing payment

Cash Accounting Scheme

• VAT Return Deadline – Due 1 month and 7 days after the end of the VAT period ends, usually quarterly
• VAT Payment Deadline – 1 month and 7 days after the VAT period ends

Flat Rate Scheme

• VAT Return Deadline – Due 1 month and 7 days after the end of the VAT period ends, usually quarterly
• VAT Payment Deadline – 1 month and 7 days after the VAT period ends

Making Tax Digital (MTD) for VAT is mandatory for all VAT-registered businesses, requiring them to keep digital records and submit VAT returns to HMRC digitally using approved software.

Corporation Tax

If you operate a limited company, you must register for Corporation Tax within 3 months of starting to trade and pay Corporation Tax on your profits. Key deadlines for Corporation Tax are based on the accounting period of your company rather than fixed dates in the tax year.

Corporation Tax Deadlines:

• 9 months and 1 day after your accounting period ends – Your Corporation Tax payment is due
• 12 months after your accounting period ends – You must file your Company Tax Return (CT600)

Therefore, if your company’s accounting period ends on 31^st December 2025, your Corporation Tax payment is due by 1^st October 2026, and your CT600 must be filed by 31 December 2026. Each CT600 covers a single accounting period. This means that in a company’s first or final year of trading, it is common to have two Corporation Tax returns for that year as the accounting periods may not align neatly with the tax year.

PAYE and National Insurance

If your business has employees, you must operate Pay As You Earn (PAYE) and deduct Income Tax and National Insurance contributions at source

PAYE Deadlines

• Submit Full Payment Submission (FPS) on or before each payday
• Pay PAYE tax and NICs – 22^nd of each month if paying electronically and 19^th of each month if paying by post

For small employers averaging under £1,500 per month in total PAYE and NICs, HMRC considers you a small employer and PAYE and NICs can be paid quarterly instead of monthly. Quarterly payments are due on the 22nd of April, July, October, and January (or 19th if paying by post).

Capital Gains Tax (CGT) Deadlines

If you sell or dispose of business assets, such as property, assets, crypto or shares, you may owe Capital Gains Tax (CGT), a tax on the profit you make when an asset you’ve disposed of has increased in value.

Key CGT deadlines include:

• 60 days from completion for property disposals to report the gain and pay any CGT due
• 31^st January of the following year to report other gains via your Self-Assessment tax return and pay CGT owed

Staying aware of these deadlines helps you plan ahead and avoid unexpected tax bills that could impact your cash flow as well as staying compliant.

Stay Organised and Work with an Accountant

Meeting all your tax and reporting deadlines as well as making the switch to MTD can seem overwhelming but with the right support, you can reduce the time you spend on admin, ensure compliance and pay less tax.

Our accountancy packages are all-inclusive with deadline reminders and unlimited support and advice from your own dedicated accountant. They will expertly manage all your business and personal accounting needs, ensuring that you’re compliant and that your tax position is optimised. This gives you the breathing room to focus on your business rather than struggling with tax schedules and compliance.

FreeAgent accounting software is included at no extra cost saving you up to £330 a year, or Xero either free or at a discounted rate depending which license is best suited to your needs. Both platforms are market-leading with powerful automation and in-depth reporting functionality as well as being HMRC-approved and fully MTD-compliant.

Request a callback today to learn more or get an instant online quote.