Managing business expenses in the UK is one of the most important financial habits to establish when starting a business.
Good expense management gives you a clearer picture of what your business is actually costing to run, helps you calculate profit accurately and makes tax reporting much easier. It also gives you better information when setting prices, planning cash flow and deciding where the business can afford to spend.
The rules vary depending on whether you operate as a sole trader, partnership or limited company, so it is important to understand how expenses apply to your particular business structure.
This guide covers the main expense categories UK startups should know about in 2026, home-working costs, record keeping, Making Tax Digital and some of the common mistakes to avoid.
What counts as an allowable business expense?
For sole traders, the general principle is that an expense must be incurred wholly and exclusively for the purposes of the business.
If an expense has both business and personal use, you may be able to claim the business element where it can be clearly identified and reasonably separated. A cost with an inseparable dual purpose may not qualify.
Common business expense categories can include:
- Office costs – stationery, postage, business software and relevant phone and internet costs
- Business premises – rent, utilities, repairs and certain maintenance costs
- Travel – qualifying business journeys, parking, public transport and accommodation for business trips
- Professional costs – accountancy, certain legal fees, business insurance and relevant professional subscriptions
- Marketing – advertising, website costs, promotional materials and other qualifying marketing expenses
- Stock and materials – goods purchased for resale and materials used to provide products or services
- Staff costs – wages, employer National Insurance, pensions and other qualifying employment costs
- Training – certain training that updates or develops skills connected with your existing business
- Protective clothing and uniforms – where required for the work you carry out
Not every cost connected with running a business automatically qualifies, so it is worth checking HMRC guidance where you are unsure.
Business equipment and larger purchases
Larger purchases such as machinery, equipment, vehicles and certain other business assets can be treated differently from ordinary day-to-day expenses.
Depending on your accounting method and business structure, tax relief may be available through capital allowances rather than simply recording the full cost as a normal business expense.
This distinction becomes particularly important when buying expensive equipment, vehicles or machinery, so it is worth checking the tax treatment before completing your accounts.
Working from home as a sole trader
Many startups begin from a spare room, kitchen table, garage or home office.
If you are self-employed and use your home for business, you may be able to claim part of the costs of running your home.
There are two main approaches.
Method 1: Work out your actual business costs
You can calculate a reasonable business proportion of certain household costs.
This can take account of factors such as:
- how many rooms are used for business
- how much time they are used for business
- the proportion of utilities relating to business use
- relevant phone and internet usage
For example, if one room is regularly used as an office but also has private use, the calculation should reflect both the proportion of the property being used and the amount of business use.
This method requires more detailed records but can produce a more accurate result where working from home forms a significant part of the business.
Method 2: Use simplified expenses
Eligible sole traders and partnerships can instead use HMRC’s simplified flat-rate system.
For 2026, the working-from-home rates are:
- 25 to 50 hours a month – £10 per month
- 51 to 100 hours a month – £18 per month
- 101 hours or more a month – £26 per month
You need to work from home for at least 25 hours a month to use these flat rates.
The simplified amount covers household running costs but does not include telephone or internet expenses. The identifiable business proportion of those costs can be calculated separately.
For a small home-based startup, simplified expenses can make record keeping easier. For a business with substantial home-working costs, calculating actual costs may be more appropriate.
Working from home through a limited company
The simplified expense rates above are designed for eligible self-employed sole traders and partnerships. They are not the method used by limited companies.
If you run a limited company and regularly work from home under an arrangement with the company, the company may be able to reimburse qualifying additional household costs without creating a tax charge.
HMRC currently allows employers to pay up to £6 per week or £26 per month towards qualifying additional home-working costs without requiring evidence of the exact additional cost, provided the relevant conditions are met.
There was also an important change from 6 April 2026: employees can no longer use the previous system to claim Income Tax relief directly from HMRC for non-reimbursed additional home-working household costs.
If you operate through a limited company, keep company and personal expenditure clearly separated and speak to an accountant if you are unsure how a particular expense should be treated.
Making Tax Digital for Income Tax is now important
One of the biggest changes affecting self-employed businesses in 2026 is Making Tax Digital for Income Tax.
From 6 April 2026, sole traders and landlords with total annual qualifying income from self-employment and property of more than £50,000 are required to use Making Tax Digital for Income Tax.
Those within the rules need compatible software to create and maintain digital records of their income and expenses and send quarterly updates to HMRC.
The programme is being expanded further:
- qualifying income over £50,000 – from April 2026
- qualifying income over £30,000 – from April 2027
- qualifying income over £20,000 – from April 2028
Making Tax Digital for Income Tax applies to qualifying sole traders and landlords – it is not the reporting system used by limited companies.
Even if your new business is below the threshold, using organised digital bookkeeping from the beginning can make it much easier to track expenses, understand cash flow and prepare for future reporting requirements.
Keep your business and personal spending separate
One of the simplest ways to improve expense management is to avoid mixing business and personal spending wherever possible.
A separate business bank account makes it easier to:
- see exactly what the business is spending
- identify business transactions
- reconcile accounts
- prepare tax returns
- provide information to an accountant
- monitor cash flow
- maintain a clearer financial record
Even where a sole trader is not legally required to operate a separate business bank account, keeping business transactions separate can significantly reduce bookkeeping work.
If you operate through a limited company, separation is even more important because the company is a separate legal entity from you personally.
Business travel and commuting
Qualifying business travel can include expenses such as fuel, parking, public transport, hotel accommodation and other costs incurred for genuine business journeys.
However, normal commuting between your home and a regular permanent workplace is generally not treated as allowable business travel.
Personal journeys, fines and penalty charges are also excluded.
Travel rules can become more complicated where you work from different locations, travel directly to customers or clients, or operate partly from home, so keep clear records of business journeys.
Client entertaining
Paying for a meal, event or other entertainment for a customer might feel like a legitimate business cost, but client entertaining is generally not deductible when calculating taxable business profits.
For self-employed businesses, HMRC specifically excludes entertaining clients, suppliers and customers and event hospitality from allowable expenses.
Staff entertaining is treated differently in some circumstances, so keep employee events separate from client entertaining in your records.
Clothing
Everyday clothing is normally a personal expense, even if you buy it specifically to wear while working.
Allowable clothing costs for self-employed businesses can include:
- uniforms
- protective clothing required for the work
- costumes for actors or entertainers
Normal shoes, trousers, shirts, jackets and other everyday clothing are not normally allowable simply because they are worn for work.
Fines and penalties
Parking fines and other penalties are generally not allowable business expenses.
This applies even where the fine arose while you were carrying out business activity.
The better approach is to record these separately rather than treating them as normal business costs when calculating taxable profit.
VAT and business expenses
If your business is VAT registered, VAT adds another layer to expense management.
A VAT-registered business can generally reclaim VAT on eligible purchases used for the business. Where something has both personal and business use, only the appropriate business proportion of the VAT can normally be reclaimed.
Different rules can apply to areas such as vehicles and businesses using the VAT Flat Rate Scheme.
Keep valid invoices and receipts for VAT-related purchases and make sure your bookkeeping software records VAT correctly.
Keep proper expense records
Do not rely on your bank statement alone to remember what a payment was for months later.
Good records can include:
- invoices
- receipts
- bank statements
- mileage records
- supplier bills
- payment confirmations
- notes explaining unusual transactions
- digital copies of supporting documents
For sole traders, business records generally need to be kept for at least five years after the 31 January Self Assessment submission deadline for the relevant tax year.
Companies also have record-keeping requirements. HMRC guidance generally requires relevant company and accounting records to be retained for six years from the end of the company financial year they relate to, with longer periods required in some circumstances.
Cloud accounting and bookkeeping software can make this much easier by allowing receipts and transactions to be recorded as they happen rather than reconstructed at the end of the year.
Common expense mistakes to avoid
A few simple habits can prevent many of the problems startups face later.
Do not treat every payment from the business account as an allowable expense. A transaction still needs to meet the relevant tax rules.
Do not mix personal and business spending unnecessarily. Separate transactions are much easier to understand and record.
Keep receipts and supporting records. Make a habit of saving them when the transaction takes place.
Record expenses regularly. Leaving bookkeeping until the end of the tax year makes errors and missing information far more likely.
Be careful with mixed-use costs. Record how you calculated the business proportion rather than choosing an arbitrary percentage.
Do not assume large equipment purchases are ordinary expenses. Capital allowance rules may apply.
Keep up with digital reporting requirements. Making Tax Digital is now part of the reporting system for many self-employed businesses.
The practical takeaway
Managing expenses properly is not just about reducing a tax bill. It gives you a much clearer understanding of how much your business costs to operate and how much it needs to earn.
Build a simple system from the beginning:
- keep business spending separate
- save receipts and invoices
- record expenses regularly
- use clear expense categories
- keep track of business mileage
- understand your home-working method
- use appropriate bookkeeping software
- check unusual expenses before claiming them
The stronger your financial records are, the easier it becomes to monitor cash flow, build realistic forecasts and make informed decisions as the business develops.
For more detailed startup tax guidance, explore the free Sole Trader Tax & Startup Guide and Limited Company Tax & Startup Guide in the StratoWrite Shop.
If you are preparing to start a business, our Ready-Made Business Plans provide a structured step-by-step route for specific UK business ideas, while our Custom Business Plans are built around your individual business, goals and circumstances.
Important: Tax treatment depends on individual circumstances and rules can change. This article provides general information and is not individual tax, accounting or legal advice. Check current HMRC guidance or speak to a qualified professional where necessary.