From Side Hustle to Serious Business: Financial Steps You Can't Afford to Skip

Many successful businesses begin as a side hustle or a hobby.  What starts as a way to earn extra income alongside employment can gradually develop into something much bigger.  

Understanding when your extra income has become a business is important as that income then becomes taxable and you will be required to register for self-assessment and declare it for tax. 

When Does a Side Hustle Become a Business (according to HMRC)? 

HMRC consider that where you have income over £1k from a source other than employment then you need to look at registering for tax. If you are regularly selling products or services with the intention of making a profit, then you are carrying on a trade for tax purposes. 

Many people start by earning occasional income through: 

• Freelance work 

• Tutoring 

• Online sales 

• Consultancy 

• Content creation 

• Craft businesses 

• Property-related services 

• Trades and construction work 

Registering with HMRC 

If you are earning income from sources other than employment then it is probably time for you to register with HMRC, if you haven’t already.   Registering with HMRC is easy and is done through their website.  

Following registration HMRC will issue you with a unique tax reference number (UTR) and will ask you to start filing self-assessment tax returns.  

Selling Through Online Platforms? HMRC May Already Receive Information 

Many side hustles now operate through online platforms such as Vinted and Etsy, Airbnb and Booking.com. What some sellers may not be aware of is many of these platforms are now required to collect and report information about users and their income direct to HMRC under international reporting rules. 

This does not automatically mean tax is due on every sale, but where you are regularly selling goods or services, HMRC may use the information provided by platforms to help identify trading activity.  Where they feel you are a trading business they will send you a letter asking for more information. 

It should be noted that selling unwanted personal possessions is often treated differently from running a business and selling your old furniture when upgrading isn’t going to create taxable income.  

Keeping Proper Records from Day One 

Where you are trading and have reporting requirements then good record keeping is best practice no matter how big or small your business venture.  Accurate records help ensure tax returns are completed correctly, allowable expenses are identified and deducted before tax is calculated.  

Important records may include: 

• Sales invoices 

• Receipts 

• Bank statements 

• Mileage records 

• Purchases 

• Fees & commission costs 

Understanding What Expenses You Can Claim against tax  

Don’t miss out on understanding the expenses that are deductible from your income for tax! Allowable business expenses may include: 

• Office costs 

• Professional subscriptions 

• Marketing and advertising 

• Business insurance 

• Travel costs 

• Software subscriptions 

• Training directly related to the business 

• Equipment and tools 

The exact treatment depends on the circumstances, so obtaining professional advice can help ensure claims are accurate and compliant. 

Separate Your Business and Personal Finances 

As your business grows it is recommended that you have a separate business account, so it is easy to track business income and expenditure. 

A separate business account helps to: 

• Monitor income and expenses clearly 

• Simplify bookkeeping 

• Prepare tax returns more efficiently 

• Improve financial visibility 

• Demonstrate professionalism to customers and suppliers 

Keeping finances separate also reduces the risk of overlooking allowable expenses or taxable income. 

Plan for Tax Before the Bill Arrives 

Don’t let a tax bill be a surprise for you.  Remember that when income comes through employment, tax is usually deducted automatically through PAYE but as a business owner, you are often responsible for setting money aside yourself.  

Plan ahead and look at setting aside money regularly for Income Tax, National Insurance, Corporation Tax (where applicable) and VAT (if registered), as this can help prevent cash flow pressures and ensure funds are available when payment deadlines arrive. 

Need Help Taking Your Business to the Next Level? 

If your side hustle is becoming a serious business, now is the perfect time to review your finances and ensure the right foundations are in place.  

At Forth Accountancy, we help business owners navigate growth, manage tax obligations and build financial systems that support long-term success. 

Speak to our team today to discuss how we can help your business move confidently into its next stage of growth.