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    TaxKilnUK tax guidance
    TaxKilnUK tax guidance

    Cash Basis Accounting

    From 6 April 2024 (2024/25 tax year onwards), cash basis accounting is the DEFAULT method for all sole traders + unincorporated partnerships, you must actively opt out if you want to use accruals basis (election via SA103F box 8). Cash basis records income when actually RECEIVED + expenses when actually PAID, rather than the matching/accruals principle of recognising earned income + incurred costs across periods. The turnover threshold has been REMOVED entirely (previously: enter at ≤£150,000, exit at >£300,000), businesses of ANY turnover can now use cash basis. From 2024/25, cash basis losses can be used in the same way as accruals losses, sideways relief (s.64 ITA 2007), carry-forward, opening years relief all now available. The previous £500 interest cap was also removed. Exclusions remain: LLPs, corporate partnerships, Lloyd's underwriters, businesses using farmers'/artists' profit averaging, businesses with active R&D allowance claims, ministers of religion.

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    Guidance, not advice. We explain the rules, we don't assess your situation. Always seek financial or tax advice from your accountant, or contact HMRC. Read our editorial scope →

    What this relief is, in plain English

    Cash basis is the UK's simplified accounting method for unincorporated businesses, made default from April 2024 to reduce small-business compliance burden. The mechanic: track money IN when you actually receive it, track money OUT when you actually pay it. No invoices-in-progress, no debtors/creditors at year-end, no matching-principle adjustments. For most simple sole traders + small partnerships, cash basis matches how they actually think about their business + how they manage cash flow. The April 2024 reforms removed the previous turnover thresholds (entry ≤£150k, exit >£300k) entirely + extended cash basis to businesses of any size. The previous £500/year interest deduction cap was also removed, interest is now fully deductible if 'wholly + exclusively' for business purposes. Trading losses on cash basis from 2024/25 can be used in the same ways as accruals losses, sideways relief, carry-forward, opening-years carry-back all available. These changes effectively removed the historic disadvantages of cash basis vs accruals + made the simpler method genuinely advantageous for most small businesses. The practical decision for sole traders now is whether to actively opt OUT of cash basis (via SA103F box 8 election) to use accruals. The cases where opt-out makes sense are narrow: substantial stock/WIP businesses where matching matters; businesses needing GAAP-compliant accounts for bank lending; complex pre-payment/deferred-income arrangements. Most sole traders should stay on cash basis + benefit from the simpler bookkeeping + automatic application from 2024/25 onwards.

    How it works

    Default from 6 April 2024, must opt out for accruals

    Cash basis is automatic for sole traders + unincorporated partnerships from 2024/25 onwards. No election required to use cash basis. To use accruals basis instead, file a formal election on the Self Assessment return, SA103F box 8 (sole traders) or SA800 equivalent (partnerships). Election is annual, doesn't carry forward automatically. Many accountants opt out by default for new clients with complex accounts; many small DIY-bookkeepers stay on cash basis without realising it's the default.

    Income when received, expenses when paid

    Cash basis recognises income on the date money is actually received in the business bank account (or cash + cheque equivalent date). Issuing an invoice doesn't create cash-basis income, only the customer paying it does. Expenses are recognised when the supplier is actually paid, not when the invoice is received. Most simple service-based or small-product sole traders find this matches their natural cash-flow understanding of the business + reduces year-end bookkeeping complexity.

    Capital items deducted on payment, not via allowances

    Under cash basis, most plant + machinery + equipment is deducted IMMEDIATELY when paid for, no AIA pool, no WDA, no carry-forward of unused allowances. Simpler but less flexible than accruals + AIA. CARS are an exception: cannot be immediately deducted under cash basis. For cars, use either simplified expenses (45p/25p mileage) OR actual costs apportioned by business use + capital allowances via main pool / special rate pool / EV FYA. Land + buildings + intangibles + most other capital items have their own specific rules outside cash basis simplification.

    Losses fully usable (April 2024 reform)

    From 2024/25 onwards, cash basis trading losses can be used in ALL the same ways as accruals losses: sideways relief (ITA 2007 s.64) against other income in current or prior year; extension to capital gains (s.71); carry-forward against future profits of the same trade (s.83); opening-years carry-back for first 4 years of trade (s.72); terminal loss relief on cessation (s.89). The previous cash-basis restrictions on sideways + carry-back relief are gone. The £50,000 / 25% of ATI cap on sideways relief continues to apply (not cash-basis-specific). This loss-relief alignment makes cash basis a viable choice even for businesses in loss-making early years.

    Who qualifies

    Interactions with other reliefs

    Trading Allowance + Property Allowance

    Both £1,000 allowances operate independently of accounting basis. Under cash basis or accruals, you can elect to claim the £1,000 allowance instead of actual expenses on each trade or property income source. The allowance test is against gross receipts in the year, same definition regardless of basis.

    Simplified Expenses

    Simplified Expenses (£10-£26/month WFH, 45p/25p mileage, £350-£650/month live-at-business-premises) are independent of accounting basis, claimable under cash basis OR accruals. Most cash-basis sole traders use Simplified Expenses for the categories they qualify for, then actual costs for everything else.

    Capital Allowances (AIA, Full Expensing, WDA)

    Under accruals basis, most plant + machinery uses AIA (£1m/year) + WDA mechanics. Under cash basis, most capital items are deducted immediately on payment, simpler but no carry-forward of unused allowances. CARS are excluded from cash-basis immediate deduction, they require simplified expenses (mileage) OR actual costs + capital allowances regardless of basis.

    MTD-ITSA Phase 1 (April 2026 onwards)

    Cash basis profits determine MTD-ITSA qualifying income test the same way as accruals profits, combined gross income above £50,000 (Phase 1 from April 2026) triggers MTD-ITSA requirements. The simpler bookkeeping of cash basis aligns well with the quarterly digital update requirement of MTD-ITSA, many MTD-compatible software packages are cash-basis-native.

    Common mistakes + audit triggers

    Worked example

    Ola, Manchester - Self-employed graphic designer transitioning from accruals to cash basis in 2024/25 (2024/25 (transition year))

    Ola has run her sole-trader graphic design business since 2020 using accruals basis. April 2024 brings the cash basis default. Her 2024/25 figures: gross invoiced income £42,000; cash actually received £38,000 (£4,000 of December-March invoices unpaid at year-end); business expenses paid £8,500; opening debtors carried forward from 2023/24 (accruals) = £3,500 (clients who paid in 2024/25 for work invoiced in 2023/24); opening creditors carried forward = £600 (suppliers she paid in 2024/25 for invoices received 2023/24).

    Calculation: **Cash basis profit calculation (2024/25):** Cash received in year: £38,000 Less: Opening debtors collected in year (already taxed under accruals 2023/24): -£3,500 = Cash basis income subject to tax this year: £34,500 Cash payments to suppliers in year: £8,500 Less: Payment of opening creditors (already deducted under accruals 2023/24): -£600 = Cash basis expenses deductible this year: £7,900 **Cash basis taxable profit 2024/25: £34,500 - £7,900 = £26,600** **Comparison if she had stayed on accruals:** Accruals income: £42,000 (invoiced + earned in year) Accruals expenses: £8,500 (received + accrued in year) Accruals taxable profit: £33,500 **Net effect of cash basis transition:** Cash basis defers £3,500 of December-March invoiced-but-unpaid income to 2025/26 (when actually paid). No double counting of opening debtors (£3,500 already taxed in 2023/24). Result: 2024/25 profit £26,600 vs hypothetical accruals £33,500, £6,900 difference, mostly due to year-end timing. **Tax saving in 2024/25 (deferred to 2025/26):** If Ola is basic-rate, 20% × £6,900 = £1,380 of tax DEFERRED to 2025/26 (not avoided). In 2025/26, when the £4,000 of late-payment invoices clear + the £3,500 opening-debtors reversal completes, the deferred tax catches up. **Strategic note:** Cash basis transition is not a tax-saving manoeuvre per se, it's a TIMING shift. Long-term tax liability is the same; the year-by-year recognition pattern changes. The genuine benefit is bookkeeping simplification + loss-recognition flexibility (now equal to accruals from 2024/25).

    Statute reference: Income Tax (Trading and Other Income) Act 2005 + Finance Act 2024 ITTOIA 2005 ss.31A-31F + Chapter 3A (as amended). HMRC manual: BIM70005 onwards.

    Frequently asked questions

    What happens if I miss the Self Assessment deadline?+
    The Self Assessment deadline is 31 January (online filing) for the previous tax year. Miss it and HMRC apply an automatic £100 penalty. Beyond that: £10 per day from 3 months late (capped at £900), 5% of tax due at 6 months late, and another 5% at 12 months late, under Schedule 55 of the Taxes Management Act 1970. If you have a genuine reason (serious illness, bereavement, technical issue with HMRC's systems) you can appeal with evidence; HMRC accepts reasonable excuse appeals in most genuine cases.
    Do I need an accountant or can I file Self Assessment myself?+
    Legally you can file Self Assessment yourself via gov.uk for free, most simple sole-trader returns (single income source, basic expenses) are realistic to self-file. An accountant adds real value when: your trading profit is above £40,000 (extraction-strategy decisions matter), you have multiple income streams (PAYE + self-employment + property + dividends), you've crossed the £90,000 VAT threshold, you're considering incorporation, or you have an HMRC enquiry. Expect to pay £400-£1,500/year for a typical sole-trader accountant; the cost is itself a deductible expense.
    How do payments on account work?+
    When your Self Assessment tax bill exceeds £1,000 for the first time, HMRC requires payments on account toward NEXT year's tax. Half the current bill is due 31 January (alongside the current bill); the other half is due 31 July. So your first January after crossing the threshold can hit with a double-bill: last year's balance + first payment on account. Adjust via Form SA303 if you expect next year's income to drop substantially. Payments on account don't apply if more than 80% of your tax is collected via PAYE.
    Why would I opt OUT of cash basis if it's the default?+
    Accruals basis is preferable if you have: (1) Substantial stock or work-in-progress where matching costs to revenues matters for accurate profit measurement. (2) Significant trade debtors (invoiced but unpaid), under cash basis you can't recognise income until paid, which may distort year-end position. (3) Bank lending requirements demanding GAAP-compliant accounts (banks often require accruals for management accounts). (4) Complex pre-paid expenses or deferred income arrangements. Most simple service-based sole traders + small product businesses are well-suited to cash basis, the simplicity outweighs the matching-principle benefits. Election to use accruals is via SA103F box 8 on each year's Self Assessment return. The election is annual + doesn't carry forward, you must elect each year you want accruals.
    How do I handle the transition from accruals to cash basis (first year of mandatory cash basis 2024/25)?+
    Transitional adjustments needed to avoid double-counting. Opening DEBTORS (income earned + recognised under accruals but not yet received) are excluded from cash basis year-one receipts, they've already been taxed under accruals in earlier years. Opening CREDITORS (expenses incurred + recognised under accruals but not yet paid) are excluded from cash basis year-one payments, they've already been deducted. Opening STOCK is deducted in the year it's PAID FOR (typically year 1 of cash basis), even if previously held as stock under accruals. HMRC's BIM70005-BIM70080 guidance (June 2024) confirms adjustments must be made on a 'just and reasonable basis'. Most sole traders making the transition see a one-off adjustment in 2024/25; accountants typically handle this automatically via their software.
    Can I claim capital allowances (AIA, WDA) under cash basis?+
    Different mechanic. Under cash basis, MOST capital expenditure (plant, equipment, vehicles other than cars) is deducted IMMEDIATELY as an expense in the year of payment, no AIA pool, no WDA, no carry-forward. This is simpler but less flexible than accruals basis where AIA + WDA mechanics let you smooth deductions over time. EXCEPTIONS: cars are NOT immediately deductible under cash basis, vehicles either use simplified expenses (45p/25p mileage) or actual costs apportioned with capital allowances (via WDA in the main pool 18% or special rate pool 6%; cars excluded from AIA + Full Expensing). Land + buildings + intangibles aren't deductible under cash basis directly; they're capital items requiring different treatment.
    Does cash basis affect my Class 2 / Class 4 NI calculation?+
    No, cash basis profits determine NI calculation the SAME way as accruals profits. Profits below £6,845 Small Profits Threshold = no compulsory NI (voluntary Class 2 available). Profits £6,845-£12,570 = automatic NI Credit. Profits above £12,570 = Class 4 at 6% (up to £50,270) + 2% above. The choice of accounting basis doesn't change the thresholds or the rates. Cash basis can affect WHEN profits are recognised (cash receipt vs invoice raise), so could shift a marginal-profit year between bands, but the structure is identical. For NI planning, focus on overall annual profit position regardless of accounting basis.

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