When you start out as a sole trader in the UK, there is no shortage of decisions to make: which expenses to claim, whether to register for VAT, how to handle payments on account. But few choices have as quiet and lasting an impact as how you decide to record your income and expenditure. The two options HMRC permits for Self Assessment purposes are cash basis and accrual accounting (also called traditional accounting). Each has genuine advantages — and genuine pitfalls. Understanding the difference is not just a bookkeeping detail; it shapes your tax bill, your cash flow picture, and your administrative burden from day one.
What Is Cash Basis Accounting?
Cash basis accounting is exactly what it sounds like: you record income when money actually lands in your bank account, and you record expenses when you actually pay them. Nothing is recognised before cash changes hands.
HMRC introduced the cash basis scheme specifically to simplify record-keeping for small businesses. To be eligible, your turnover must not exceed £150,000 per year (rising to £300,000 under certain conditions). Once your turnover goes above £300,000, you must switch to accrual accounting.
Consider a self-employed graphic designer in Manchester who completes a logo project in March but doesn't receive payment until April. Under cash basis, that income appears in the April tax year — not March. Equally, if she orders a new drawing tablet in late January but pays for it in February, the expense sits in February's records. Simple, intuitive, and broadly aligned with how money actually flows through the business.
The main advantages of cash basis for sole traders are:
- Simplicity — no need to track debtors or creditors separately
- Tax timing — you only pay tax on money you have genuinely received, reducing the risk of a tax bill on an unpaid invoice
- Lower admin overhead — fewer year-end adjustments are required
The drawbacks are less obvious but worth knowing. Interest deductions on loans are capped at £500 per year under the cash basis scheme, which can hurt sole traders who have borrowed to invest in equipment or premises. You also cannot carry back losses in the same way, which may disadvantage anyone in a volatile industry.
What Is Accrual (Traditional) Accounting?
Accrual accounting follows a different principle: income is recognised when it is earned and expenses when they are incurred, regardless of when money actually moves. This is the standard method used by limited companies and is mandatory once a sole trader's turnover exceeds the cash basis threshold.
Using the same Manchester designer as an example: if she raises an invoice in March, that income goes into the March accounts — even if the client pays in April. If she receives a supplier invoice in January, the expense is recorded in January even if the direct debit doesn't leave her account until February.
This approach gives a more accurate picture of business performance in any given period. Revenue is matched to the costs incurred in generating it — a concept accountants call the matching principle. It also means your accounts reflect outstanding debtors (money owed to you) and creditors (money you owe), which is essential for businesses with significant credit terms.
The trade-off is complexity. You need to maintain aged debtor and creditor reports, account for prepayments and accruals at year end, and potentially pay tax on invoices your clients haven't yet settled. For a sole trader running a small consultancy with tight margins, that last point can cause genuine cash flow strain.
Key Differences That Actually Matter in Practice
Theory is one thing; the day-to-day reality is another. Here are the practical differences that tend to catch sole traders out:
- Bad debts — Under accrual accounting, you can claim relief for bad debts (invoices you've given up chasing). Under cash basis, bad debts don't arise in the same way because you never recognised the income in the first place. This is actually an advantage of cash basis that's often overlooked.
- Stock and work in progress — Businesses with significant stock — a sole trader baker buying flour in bulk, for instance — may find accrual accounting gives a truer picture of profitability, since it matches the cost of ingredients to the revenue from sales.
- Capital expenditure — Under cash basis, the cost of most equipment is deducted in full in the year of purchase (similar to Annual Investment Allowance). Under accrual accounting, capital items go through the capital allowances regime, which can sometimes defer relief.
- Switching methods — Changing from cash basis to accrual (or vice versa) part-way through your trading life requires transition adjustments to avoid double-counting income or expenses. It is doable, but worth discussing with an accountant before you make the switch.
HMRC's Rules and Self Assessment Implications
Both methods are acceptable to HMRC for sole trader Self Assessment returns, reported on the SA103 supplementary pages. You simply indicate which basis you are using in the relevant box. However, once you opt into cash basis, you remain in it each year unless you actively elect to leave — so it is worth making a considered choice upfront rather than defaulting without thought.
For VAT-registered businesses, the picture is slightly different. The VAT Cash Accounting Scheme operates on similar logic to cash basis income tax accounting, meaning VAT is accounted for when money is received or paid rather than when invoices are raised. You can use the VAT Cash Accounting Scheme alongside either the income tax cash basis or accrual method — they are separate elections. Your VAT turnover threshold for this scheme is currently £1.35 million.
Platforms like BizHub365 handle both methods natively, letting you choose your preferred accounting basis when you set up your account. The double-entry bookkeeping engine adjusts automatically, and when it comes to MTD for VAT or your Self Assessment return, the correct figures flow through without manual recalculation. That kind of infrastructure matters most at year end, when the last thing you want is to be reconciling spreadsheets at midnight.
So Which Method Should You Choose?
There is no single right answer, but there are clear patterns that point towards one method or the other.
Cash basis is likely the better fit if you:
- Are a new or early-stage sole trader with turnover well below £150,000
- Run a service business with few or no physical stock requirements (a freelance copywriter, a dog groomer, a personal trainer)
- Want simplicity and minimal year-end admin
- Have experienced cash flow issues with clients paying late
Accrual accounting is likely the better fit if you:
- Are approaching or exceeding the £150,000 threshold and anticipate growth
- Have significant stock, work in progress, or long payment terms
- Plan to move from sole trader to a limited company in the near future (limited companies must use accrual)
- Want to produce accounts that can support a mortgage application or external funding request, where banks expect to see accrual-based figures
It is also worth having a conversation with a qualified accountant — particularly if your circumstances are anything other than straightforward. The choice affects not just your admin load but your tax liability in specific years, especially if your income fluctuates seasonally.
Conclusion: Make a Deliberate Choice, Not a Default One
Most sole traders drift into cash basis accounting simply because it is the default on many software platforms and feels intuitive. That is not necessarily wrong — for many small service businesses, it genuinely is the most appropriate method. But it should be a deliberate decision, not an accidental one.
Take stock of your turnover trajectory, your industry, your appetite for admin, and your plans for growth. If you are already using accounting software, check which basis it currently applies — you may be surprised. Whether you choose cash basis for its simplicity or accrual accounting for its accuracy, what matters most is that your records are consistent, your Self Assessment return is correct, and you are not left scrambling for receipts every January. Get the foundations right, and everything else becomes considerably more manageable.