With April in full swing and the new 2025/26 financial year well underway, we thought now would be the perfect time for a refresher on everything you need to know for the new tax year. From important tax dates and changes to trading allowance changes to compliance tips and a round-up of Spring Statement announcements, this is a small business owner’s go-to guide for navigating the year ahead.  

Key Tax Dates for the New Tax Year 

February saw changes to Alcohol Duty, March saw the introduction of new workplace recycling rules, but what can be expected for the rest of the year? 

6th April 2025 

• Start of the new tax year 

• National Insurance Contribution (NIC) reforms – employer NIC rates have risen from 13.8% to 15% while the salary threshold at with NICs become payable has been reduced from £9,100 to £5,000 per employee. 

• Capital Gains Tax (CGT) reduced – entrepreneurs selling their businesses or business assets will face increased disposal relief rates, currently 14% and rising to 18% from 2026. 

31st May: P60 deadline 

All employers must provide their employees with a P60 (a document summarising total pay and deductions for the tax year) by the 31^st May each year. Failing to do so could mean you face hefty HMRC fines.  

31st July 2025: deadline for second payment on account for 2024/25 

As a self-employed individual, if you pay tax via payment on account, you’ll need to make your second payment for the 2024-25 tax year by midnight on 31^st July. The amount paid is only an estimate based on your earnings from 2023-24 so if there’s still outstanding tax then a further balancing payment will be due on 31^st January 2026. 

5th October 2025: deadline to register for self-assessment if you’re newly self-employed 

If you’re newly self-employed or a new business owner, be sure to register for self-assessment by this date to avoid penalties.  

31st October 2025: paper self-assessment tax return deadline 

If you’ve chosen to file your self-assessment by paper, be sure to complete it and send it off in plenty of time as blaming late post won’t get you out of a late submission penalty if it doesn’t reach HMRC in time! 

October 2025: Autumn Budget 

The government has confirmed it will hold one fiscal event each year in the autumn. The exact date is yet to be confirmed, however, you can expect it to be around the end of October.  

31st January 2026: online self-assessment deadline & tax payment deadline for 2024/25

Most people opt for an online submission for their self-assessment, the deadline for which is January 31^st. You must also pay outstanding taxes due on this day. 

5^th April 2026: end of 2025/26 tax year 

Keeping track of tax deadlines and legislative changes is crucial if you want to stay compliant and avoid penalties. Be sure to mark these days in your calendar and keep an eye on them throughout the year so the deadlines don’t sneak up on you! 

Small Company Threshold Changes & IR35 Impact 

Criteria defining a small company has changed as of 6^th April this year. The following table illustrates the changes between old and new criteria. To be classed as a small company, you must meet a minimum of two of the following criteria:  

	Pre 6th April 2025	From 6th April 2025
Annual Turnover	Max £10.2million	Max £15million
Balance Sheet Total	Max £5.1million	Max £7.5million
Number of Employees	No more than 50	No more than 50

These changes could affect your reporting and tax obligations. These revised thresholds are part of aligning UK standards more closely with international benchmarks. If you now exceed two of these thresholds, you may need to prepare audited accounts and additional disclosures. 

Spring Statement 2025 

Wider announcements included the following: 

• Growth forecast: The OBR has cut growth forecasts for 2025 from 2% to 1%.  

• Capital spending increase: An increase of £2billion a year relative to the plans set out in the autumn is expected.  

• Inflation: Forecast to be 3.2% in 2025 (up from 2.6% forecast in October) and falling to 2.1% in 2026, returning to the Bank of England’s 2% target from 2027. 

Overall, there were no curveballs or big changes introduced, with this statement acting as more of an update than a full-blown budget. 

Trading Allowance & Reporting Thresholds 

The trading allowance was first introduced to support those earning relatively low amounts from casual trading, such as babysitting, selling goods online (e.g. Vinted or eBay), or other ad hoc work. Many people who have a side hustle alongside their main income job benefit from the trading allowance. 

The trading allowance is set at £1,000 which means that if you earn under this threshold, you don’t need to pay tax or National Insurance on this income. If, however, you regularly make a profit from your side hustle and earn over £1,000 in one tax year from sales, you will need to report this on your self-assessment tax return (SATR) and the income will be subject to tax. Always make sure you keep accurate records so you can keep track of your expenses and sales. 

While the tax-free trading allowance of £1,000 will stay the same, the government has recently announced changes to the reporting threshold which will rise from £1,000 to £3,000. What does that mean? Those earning less than £3,000 won’t need to register for or submit a SATR. Those with taxable income below the £3,000 threshold will have the choice to report tax through a new digital reporting service or remain with the self-assessment.   

5 Tips for Running Your Small Business Compliantly 

For the newbie business owners amongst you, we thought we’d impart some wisdom so that you can operate confidently and compliantly from day one. 

1. Separate your business and personal finances by opening a dedicated business bank account. This will help you track expenses and make life easier when it comes to filling out and submitting your self-assessment tax return.  

2. Keep on top of your finances by practicing good bookkeeping.  

3. Mark your calendar with important deadlines so you don’t miss key dates. 

4. Always make sure you read the fine print and check contracts, whether that’s for your employees or for clients. 

5. Stay informed on the latest industry news – knowing what changes are incoming will help to inform your key business decisions. 

We regularly publish blogs and guides that will give you the tips and advice you need to help stay abreast of important developments. Make sure you check back regularly to our blog page to find news and updates. 

Making Tax Digital 

There have been many developments on the Making Tax Digital (MTD) for Income Tax rollout which is set to happen in April 2026. What’s to change? Sole traders and landlords with earnings over £50,000 per year will need to start reporting expenditure and income to HMRC digitally via Income Tax compliant software.  

If this will affect you, now is the time to start preparing your digital systems and getting used to using compatible software. That means that by 2026, you’ll be practiced at submitting quarterly updates and you won’t be caught out. 

Important to note: qualifying income will be based on the 2024/25 tax year. 

Top 5 Changes Impacting Small Businesses in 2025 

Before we wrap up, here’s a rundown of some of the most important changes happening this year that you may be affected by. Most of these have been mentioned across the blog already, so we’ll keep this round-up brief. 

New small company thresholds – these could change your reporting requirements. 

MTD for Income Tax – preparing for the use of new digital tax systems is a must. 

Scrutiny on side hustle tax – HMRC is cracking down on side hustle tax and undeclared income so making sure you’re on top of your taxes and reporting any income over the trading allowance is crucial. 

Employment allowance changes – increases from £5,000 to £10,500 this tax year which could have a real impact in reducing your tax bill. Employers can claim this allowance to reduce their secondary Class 1 National Insurance contributions. Find out more here. 

National Insurance Contributions increase – from 13.8% to 15%. This applies to contributions made by employers for each individual employee. 

Final Thoughts 

The new 2025/26 tax year is shaping up to be a transformative one for small businesses especially. Whether you’re a new business owner or a seasoned entrepreneur, taking some time to step back and assess how these changes will affect the way you run your business is crucial. 

Need help getting your taxes in order? Reach out to our team of expert accountants regarding any queries – big or small.