Tax library · November 2, 2026

UK Business Expenses: Evidence to Prepare for Your Tax Return

An expense description in bookkeeping software is a starting point, not proof that a deduction is correct. A useful tax file explains what was bought, who paid, why it related to the business, which period it belongs to, and how any personal element was handled. Those questions matter whether you run a sole trade or a limited company, although the applicable tax rules are not identical.

This guide focuses on evidence and review. It does not provide a universal list of purchases that every business can deduct. A well-organised file helps an adviser assess a claim accurately instead of choosing treatment from a bank reference or a label such as miscellaneous.

Identify the taxpayer and the accounting approach

Start by confirming whether the expense belongs to you as a sole trader, to a partnership, or to a limited company. A company director is not treated as self-employed merely because they own the business. The distinction affects how costs are recorded, reimbursed, and considered for tax. HMRC’s self-employed expenses guidance makes that scope clear and should not be applied indiscriminately to a company.

Tell the preparer which accounting method and period the records use. A payment date, invoice date, and service period can all be relevant in different ways. Mark deposits, advance payments, finance arrangements, and invoices covering more than one period for review. Do not move a purchase into a preferred year simply because the business had more profit there. Keep the factual dates and let the correct rules determine the treatment.

Keep evidence of both the purchase and payment

Save an invoice or receipt that identifies the supplier, item or service, amount, and date. A bank or card statement can support that the payment occurred, but it may not show what was purchased. For a large or unusual cost, retain the contract, order confirmation, and explanation of the commercial purpose. Connect the documents through a reference in the expense schedule so someone else can inspect the transaction efficiently.

Keep evidence readable and complete. A photograph cutting off the supplier or total creates avoidable questions. If a supplier reissues a document, retain enough information to avoid counting both versions as separate costs. Where someone paid personally for a company expense, show the purchase and subsequent reimbursement as linked transactions. Otherwise the same cost can appear once in the director’s claim and again when the company repays them.

Explain the business purpose at the time

A short contemporaneous note can clarify a cost that would otherwise be difficult to understand months later. Record the project, customer meeting, business activity, or equipment use involved. A vague phrase such as for work may be insufficient where the item has an obvious private use. The note should explain the actual purpose, not reproduce a deduction category in the hope that the category proves the claim.

For training, subscriptions, professional advice, or marketing work, keep the scope and connection to the business activity. Different categories can raise different tax questions, so give the adviser the materials needed to review them. If you are unsure, put the item on a questions list. Leaving a cost visible for review is better than either claiming it aggressively without support or omitting a legitimate cost because you did not understand the rule.

Make mixed-use calculations traceable

Phones, internet, vehicles, and premises can involve both business and personal use. Provide the total cost and the basis of any proposed split. Avoid using the same round percentage every year without checking whether circumstances changed. A record of usage, bills, business locations, or relevant time periods may help explain the approach. The adviser should be able to understand how the claimed amount follows from the evidence.

Different methods may be available for some categories and taxpayers. Do not combine incompatible approaches or claim the same underlying cost twice. Ask which method is being used and what records it requires. Keep the calculation with the invoices and note any change from an earlier year. A consistent evidence trail is valuable, but consistency does not justify continuing an approach that no longer reflects the facts or the applicable rules.

Treat travel as a documented journey

Keep the journey date, destination, purpose, and relevant mileage or ticket information. Distinguish business travel from personal trips and ordinary travel between home and work. HMRC’s self-employed travel guidance identifies costs that may be allowable and exclusions, but a journey still needs to fit the relevant facts. Writing client visit on an expense claim without knowing which client or where the trip occurred weakens the record.

For trips mixing business and private activities, keep the itinerary and explain both elements. Hotel and meal costs should be linked to the trip and reviewed under the relevant rules, not assumed deductible whenever you were away from home. Vehicle purchase, finance, and running costs may also need different treatment from a rail ticket. A complete travel log helps the adviser choose the correct analysis instead of applying one general rule to every transport payment.

Separate assets, stock and running costs

A new computer, equipment purchase, or property improvement may need different accounting and tax treatment from a monthly subscription or repair. Keep the invoice, date brought into use, financing details, and intended business use. If an asset replaced another item, identify what happened to the old one. A bank export generally does not contain the information needed to review allowances, disposal consequences, or the distinction between improvement and repair.

For goods purchased for resale, retain stock and purchase records as well as sales evidence. If the business holds goods at the period end, explain how the stock figure was established under the applicable approach. Missing inventory information can distort a profit review even when every supplier payment has been recorded. Do not treat a large stock order as proof of an immediate deduction without considering the accounting method and relevant rules.

A hypothetical expense-file review

Consider a small consultancy with a mixed personal and business phone, a new laptop, rail travel, and several purchases made on the owner’s card. Its first spreadsheet contains totals headed office, travel, and equipment. The reviewer cannot tell which phone amounts are business related, whether travel was to a customer or the ordinary workplace, or whether a reimbursement duplicated a purchase already entered from a company card feed.

The owner rebuilds the schedule using one transaction per line. Phone bills are linked to a usage explanation. Each journey has a date, destination, and purpose. The laptop is flagged as an asset purchase with the invoice and date of first business use. Personally paid costs are connected to the expense claim and reimbursement. A missing receipt is identified as missing rather than replaced with a document downloaded for a different purchase.

The adviser then reviews the correct treatment using the taxpayer’s legal structure and accounting method. Some amounts may be allowable, some may require adjustment, and some may need further evidence. The example does not establish an entitlement to deduct every item mentioned. It shows how a factual record makes the review more accurate and reduces the risk of omissions, duplication, or unsupported assumptions about personal spending.

Handle lost documents without inventing evidence

First ask the supplier or platform for a replacement. Check email, account downloads, and transaction histories. If no replacement is available, keep a reconstruction note stating what happened, the amount, the date, the business purpose, and the evidence that remains. Explain the gap to the preparer. Do not alter a different invoice, create a false receipt, or claim that a guess is an exact documented amount.

The treatment of incomplete evidence depends on the circumstances and the obligation being considered. An adviser may ask for further corroboration or decide an entry cannot be supported as proposed. Keep that decision with the records and correct the process for future purchases. A clear exception list is preferable to hiding incomplete entries inside a large category total where nobody can identify the underlying uncertainty.

Review company costs for personal consequences

For a company, a business purchase can also raise questions about employment benefits, director transactions, or reimbursements. An expense in the company accounts is not automatically free of personal reporting consequences. Record who used the item and who benefited from the payment. Where the company paid a personal bill, flag it directly rather than assigning it an artificial business description to make the reconciliation easier.

Maintain the company evidence required for accounts and tax review. The company records guidance describes the broader accounting-record responsibilities. Ask who keeps the invoices and working schedules if an adviser or software provider changes. Access to a public accounts filing will not replace the transaction-level evidence needed to explain a deduction or a director’s account balance.

Frequently asked questions

Is a bank statement enough to claim an expense?

It may support payment but often does not establish the item, business purpose, or correct tax treatment. Keep the invoice and a practical explanation where necessary. More detailed evidence is especially useful for mixed-use, unusual, or high-value transactions.

Can I deduct personal withdrawals as an expense?

For a sole trader, money taken for personal use is not an operating expense simply because it leaves the business account. For a company, the payment needs its actual legal and tax classification reviewed rather than being treated as sole-trader drawings.

How can I prepare for an expense review?

Make a transaction schedule, link documents, and separate uncertain or mixed-use items. You can contact Litmus with a summary of the business structure and records available. Keep detailed invoices and private financial information for a secure review process.