Taxation (UK) · Income from self-employment

Adjustment of Profits for Tax Purposes in TX-UK

Updated 11 October 2026 · Fact-checked

Adjustment of profits turns the accounting profit into the tax-adjusted trading profit. You start with net profit, add back expenses that are not deductible for tax (private, entertainment, capital, depreciation, most gifts), deduct income that is not taxable trading income, then deduct capital allowances separately.

Understand Adjustment of Profits for Tax Purposes

Accounts are prepared under accounting rules. Tax is charged under tax rules. The two do not always agree, so you adjust the accounting profit to find the tax-adjusted trading profit.

The basic test is whether an expense is incurred wholly and exclusively for the purposes of the trade. If part is private, that part is disallowed. If the cost is capital rather than revenue, it is disallowed too. Revenue expenditure is day-to-day running cost, such as repairs and wages. Capital expenditure buys or improves an asset that lasts. Capital costs get relief through capital allowances, not through the profit adjustment.

You also remove income that is not trading income, such as bank interest or rent. These are taxed under other headings, so you deduct them from the trading profit and tax them elsewhere. Profit on disposal of a fixed asset is also deducted, because it is dealt with as a chargeable gain or through capital allowances.

Common disallowed items include: depreciation and amortisation, private use by the owner, client and supplier entertainment, gifts (unless they are to employees, or to customers costing no more than £50 per person per year, carry a conspicuous advert and are not food, drink, tobacco or vouchers), fines and penalties, and legal costs of a capital nature, such as buying property or acquiring a lease of more than 50 years. Staff entertainment is allowable. Legal costs for debt collection and normal trading are allowable. Legal costs of acquiring or renewing a lease of 50 years or less are also allowable.

Sole traders may instead use the trading allowance of £1,000. If gross trading income is £1,000 or less, it is fully exempt from tax. If it is more, you can choose to deduct £1,000 from your gross income instead of deducting your actual expenses. If you claim the allowance, you get no deduction for actual expenses. You pick whichever gives the lower profit, which means the greater of £1,000 or your actual expenses. The allowance is not available against income from a partnership you are a partner in.

Key rules to remember

Tax-adjusted trading profit: Net profit per accounts + disallowable expenditure − non-trading or non-taxable income − capital allowances = tax-adjusted trading profit; Capital allowances are usually deducted after the adjustment of profits. Many answers show them as a separate line.
General deduction test: Allowable only if wholly and exclusively for the trade, and revenue in nature; Mixed private and business use means the private part is disallowed.
Private use by the owner: Add back the private proportion of the expense (or the full amount if drawings are charged); For a sole trader, the owner's own wages, drawings and private costs are not deductible.
Trading allowance: £1,000 deduction from gross trading income instead of actual expenses (not in addition to them); You claim either the £1,000 or actual expenses, never both. It only matters when gross trading income is over £1,000. Choose the allowance when actual allowable expenses are less than £1,000. Otherwise deduct actual expenses.
Gifts to customers: Allowable if cost ≤ £50 per person per year, carries a conspicuous advert, and is not food, drink, tobacco or vouchers; Gifts of the above type that fail the test are disallowed.

How to solve Adjustment of Profits for Tax Purposes questions

Use the same layout every time. Work down the accounts list, line by line, and record the effect of each item.

1Start with the net profit per the accounts. Write it as the first line of your answer.
2Go through the expenses one by one. Decide if each is revenue and wholly and exclusively for the trade.
3List disallowable items in an add back column: depreciation, private use, entertainment, capital items, fines, non-allowable gifts, and capital legal costs.
4List income that is not trading income, or that is taxed elsewhere, in a deduct column: interest, rent and profit on disposal. Deduct other investment income, such as dividends, only if it was included in the accounting profit.
5Calculate any partial items, such as the private proportion of a car or phone cost.
6Total the adjustments and compute the adjusted profit before capital allowances.
7Deduct capital allowances if they are requested, then state the final tax-adjusted trading profit. Show the trading allowance comparison if the question hints at it.

Quickest way: The add back and deduct sweep

When to use it: Use this for objective test questions and for Section C when time is short and the expense list is long.

Write the starting profit.
Scan the list once and tick only items that are always disallowed: depreciation, entertainment (non-staff), fines, capital items, and drawings.
Scan again for tricky items: gifts, legal costs, private use, and bad debts (specific trade bad debts are allowable; general, non-specific impairment allowances are disallowed).
Scan for income included in the profit that is not trading income: interest, rent, other investment income and gains on disposal.
Total the adds and deducts and finish. Do not recompute allowable items, because they are already in the profit.

Common mistakes in Adjustment of Profits for Tax Purposes

Adding back allowable expenses, such as staff entertainment or repairs.
Students assume that every entertainment or repair item is disallowed.
Fix: Check who the entertainment is for. Staff entertainment is allowable. Repairs are allowable if they restore the asset, but improvements are capital and disallowed.
Deducting capital allowances inside the adjustment and again later.
The two steps are close together in the layout and students lose track.
Fix: Add back depreciation in the adjustment. Deduct capital allowances once, as the final step.
Forgetting to deduct non-trading income such as bank interest.
Students focus on expenses and ignore the income lines.
Fix: Scan the income side of the accounts every time. Anything not from the trade is deducted.
Treating all gifts to customers as allowable or all as disallowable.
The gift rules have several conditions.
Fix: Apply the test: £50 or less per person per year, a conspicuous advert, and not food, drink, tobacco or vouchers. If any condition fails, add it back.
Adding back the full cost of a mixed-use item such as a phone.
Students overlook the private proportion in the question.
Fix: Add back only the private percentage unless the whole item is private.
Using the trading allowance without comparing it with actual expenses.
Students think the allowance is automatic.
Fix: Compare £1,000 with actual allowable expenses and choose whichever gives the larger deduction, which means the lower taxable profit. You cannot claim both.

Worked examples

Example 1

Asha is a sole trader. Her net profit per the accounts is £48,000. It is after deducting: depreciation £3,000; client entertaining £1,200; staff party £900; a fine for a parking offence £150; legal fees for a new lease on her shop £700 (a 7-year lease); bank interest received £400 was included in income. Calculate her adjusted trading profit before capital allowances.

Show the solution

Start with net profit: £48,000.
Add back depreciation: £3,000.
Add back client entertaining: £1,200.
The staff party is allowable, so no adjustment.
Add back the fine: £150.
The legal fees relate to a lease of 50 years or less, so they are allowable. No adjustment.
Total add backs: 3,000 + 1,200 + 150 = £4,350.
Deduct the bank interest: £400. It is not trading income.
Adjusted profit: 48,000 + 4,350 − 400 = £51,950.

Answer: £51,950

Example 2

Ben runs a consultancy. His accounts show a profit of £30,000 after charging £2,400 of motor expenses, of which 25% is private, and £500 of gifts to customers: £300 of pens costing £10 each, each carrying the firm's logo, and £200 of hampers of food. His own drawings of £1,500 were also charged as an expense in the accounts. Compute his adjusted trading profit.

Show the solution

Start with profit: £30,000.
Private motor use: 25% × £2,400 = £600. Add back.
Pens: £10 each, under £50, with a conspicuous advert and not food or drink. Allowable. No adjustment.
Hampers: food, so disallowed. Add back £200.
Drawings: £1,500 was charged in the accounts but is not a business expense. Add back.
Total add backs: 600 + 200 + 1,500 = £2,300.
Adjusted profit: 30,000 + 2,300 = £32,300.

Answer: £32,300

Exam tips

In objective tests, the trap is usually the exception: staff entertainment, small logo gifts, or a private proportion. Read the wording before choosing.
In Section C, set out your answer in three columns or lines: item, add back, deduct. The marker awards marks for each correct treatment, so show every line, even a zero.
If a question says an item is capital, add it back and move on. Do not argue about the reasoning.
Always check whether the trading allowance gives a better result when the business is small.

Practice questions from Income from self-employment

Adjustment of Profits for Tax Purposes: frequently asked questions

What is the difference between revenue and capital expenditure for tax?

Revenue expenditure is day-to-day running cost and is deductible if wholly and exclusively for the trade. Capital expenditure buys or improves a long-term asset and is not deductible in the adjustment. It may qualify for capital allowances instead.

How does the £1,000 trading allowance work?

If your gross trading income is £1,000 or less, it is fully exempt. If it is higher, you may deduct £1,000 instead of your actual expenses, but you cannot claim both. In effect you deduct the greater of £1,000 or your actual expenses, which gives the lower taxable profit.

Is depreciation allowed for tax?

No. Depreciation is added back in the adjustment of profits. Relief for the cost of equipment comes from capital allowances.

Are legal costs always disallowed?

No. Legal costs for normal trading, such as debt collection, are allowable. Legal costs of acquiring or renewing a lease of 50 years or less are also allowable. Legal costs of buying property or acquiring a lease of more than 50 years are capital and disallowed.