What Counts as a Business Expense? A Simple Guide for Beginners

When you first start a business, one of the most common questions is about expenses. Understanding what you can and cannot claim as a business expense is important because it directly affects the amount of tax you pay. For many beginners, this can feel like a confusing area governed by complex rules.

This guide is written to give you a calm, clear overview of what an “allowable expense” is for UK businesses. It explains the core principles in plain English, provides practical examples, and helps you understand what HM Revenue & Customs (HMRC) expects. Whether you are a sole trader in Surrey/Hampshire or a limited company director elsewhere in the UK, the same fundamental rules apply.

The Core Principle: ‘Wholly and Exclusively’

The most important rule to understand is that for an expense to be allowable for tax, it must be “wholly and exclusively” for business purposes. This simply means the cost must have been incurred for your trade, and not for any other reason. If a cost has both a business and a private element, you can only claim the business part.

For example, if you have a mobile phone that you use 50% for business calls and 50% for personal calls, you can only claim 50% of the bill as a business expense. This principle is central to how HMRC looks at all business costs.

Common Examples of Allowable Expenses

While every business is different, there are many common expenses that most businesses can claim. It is helpful to be aware of these from the start so you can keep the right records.

Common examples include office costs such as stationery, postage, and business phone bills. If you have a dedicated workspace, you can claim for business premises costs like rent, business rates, heating, and lighting. For business journeys, you can claim for travel costs, including fuel, parking, and train fares, though this does not cover the daily commute to a permanent workplace e.g. travelling from your home to your office.

The cost of stock and materials that you buy to sell on to customers is also an allowable expense. In addition, you can claim for legal and financial costs like business insurance or the bank charges on your business account. To promote your business, you can claim for marketing and advertising, such as website hosting or online ads.

If you have employees, you can claim for staff costs, including their salaries and any employer’s National Insurance contributions. Finally, the cost of training courses that help you update your existing skills is usually allowable, but training for a completely new skill is not.

It is important to remember that you cannot claim for personal expenses, such as everyday clothing, meals that are not for business travel, or childcare.

What About Working From Home?

This is a very common situation for new business owners. If you work from home, you can claim a proportion of your household running costs. This can include a portion of your:

• Heating and electricity bills
• Council Tax
• Mortgage interest or rent
• Internet and telephone use

To do this, you need to find a reasonable way to divide the costs. For example, you could work out the proportion based on the number of rooms you use for business or the amount of time you spend working from home. Alternatively, HMRC offers simplified expenses, which are flat rates you can use to claim for working from home without needing to calculate the exact costs.

The £1,000 Trading Allowance

It is also worth knowing about the trading allowance. If your total income from self-employment is less than £1,000 in a tax year, you do not have to register with HMRC or pay tax on it. If your income is over £1,000, you can choose to either deduct your actual business expenses or deduct the £1,000 trading allowance from your income—whichever is more beneficial. You cannot claim both.

Common Mistakes to Avoid

Many early mistakes with expenses come from simple misunderstandings. Common errors include:

• Forgetting to keep receipts for small cash purchases.
• Claiming for costs that have a personal element without separating the business part.
• Assuming all travel is a business expense, including the daily commute.
• Not keeping any records and trying to guess your expenses at the end of the year.

Building a simple habit of keeping all your receipts and recording your expenses regularly can save a great deal of stress later on.

When Getting Advice Can Help

You are not required to use an accountant to manage your expenses. However, getting advice can be helpful if you are unsure what you can claim, you have complex costs, or you just want some reassurance that you are doing things correctly.

If you would like calm, practical support as your business develops, Penney’s Accountancy works with UK small businesses in Farnborough and the surrounding areas, helping owners understand their responsibilities and make confident decisions at every stage.

Want to Learn More in Your Own Time?

For those who want to build their confidence and understand these topics in more detail, Penney’s Finance School offers an online, self-paced business and finance course. It covers everything from company setup to cash flow and tax, allowing you to learn at your own pace.

Important information

The information provided in this article is intended as general guidance for UK businesses only and reflects UK tax legislation and HMRC guidance as of February 2026.

Tax rules and business requirements can change, and individual circumstances vary. Before acting on any of the information above, we recommend speaking to a qualified accountant who can provide advice tailored to your specific situation.