Accounting software for UK freelancers and sole traders
Self-Assessment SA100/SA103, IR35 / off-payroll rules, Flat Rate Scheme, payments on account, trading allowance, and HMRC MTD for ITSA — built for UK contractors, consultants, designers and writers.
UK freelancers face the densest personal-tax surface of any developed economy. Self-Assessment for sole traders and partnerships is administered through SA100 (main return) plus supplementary pages (SA103S for self-employment, SA103F for partners). The IR35 / off-payroll rules complicate every contract with a medium- or large-sized client since April 2021 — the client now determines the contract's status, not the contractor. Payments on account require two interim tax payments (31 January and 31 July) totalling the prior year's liability. The trading allowance gives £1,000 of tax-free trading income. And MTD for Income Tax Self-Assessment (ITSA) starts April 2026 for sole traders earning above £50,000.
UK freelancers & sole traders at a glance
| Field | Value |
|---|---|
| Authority | HMRC (Self-Assessment + VAT if registered) |
| Trading allowance | £1,000 tax-free Below this no return needed; above, full self-assessment. |
| VAT registration threshold | £90,000 (from April 2024) |
| Payments on account | 31 January + 31 July Two interim payments if prior tax > £1,000. |
| IR35 trigger | Medium or large client contracts (since April 2021) Client determines status; contractor pays through deemed-employment if inside. |
| MTD for ITSA | Mandatory April 2026 if income > £50K Threshold drops to £30K April 2027. |
Rates and thresholds verified against HMRC and gov.uk as at 2026-05-18. Re-verify after each Autumn Budget and Spring Statement.
Self-Assessment — SA100 main return + the right supplementary pages
Self-Assessment is the UK's annual personal tax return. SA100 is the main return covering employment, savings, dividends, pensions, and the various tax reliefs. Sole traders add SA103S (short — for turnover under £85K) or SA103F (full — for turnover above £85K or with more complex circumstances). Partnerships file SA800 (partnership return) plus each partner files their own SA100 + SA104S/F for their share. Landlords add SA105 (UK property income). Capital gains beyond the £3,000 annual exemption need SA108.
Filing deadline: 31 January for online filing (paper 31 October). Penalties for late filing escalate: £100 initial, daily £10 from 3 months late (capped at £900), 5% of tax outstanding after 6 months and after 12 months. HelloBooks builds the SA103 (and SA105 for landlords) from your ledger, pre-fills figures, and provides the import file for HMRC's Self-Assessment portal or your accountant's tax software.
IR35 / off-payroll rules — the contract status that drives tax treatment
Since April 2021 for medium and large clients (definition: meet 2 of: turnover >£10.2M, balance sheet >£5.1M, employees >50), the CLIENT determines whether the contract is 'inside IR35' (deemed employment) or 'outside' (genuine self-employment). Inside IR35 contracts have PAYE + NIC deducted at the fee-payer level — the worker receives net-of-tax payment as if employed. Outside contracts pay gross; the worker handles tax through their own self-assessment and pays Class 4 NIC.
HelloBooks tags each client/contract as inside/outside IR35 at the contract level and applies different tax treatment automatically. For inside-IR35 contracts the gross fee flows in but tax-and-NIC are pre-deducted; for outside contracts the gross flows in and quarterly tax accrual builds. HMRC's CEST tool (Check Employment Status for Tax) is the recommended assessment instrument but is consistently contested in the courts — a written status determination statement (SDS) from the client is critical evidence.
Payments on account, trading allowance, and MTD for ITSA
Once your self-assessment tax liability exceeds £1,000 in a year (and isn't all PAYE-deducted), HMRC requires Payments on Account: two interim payments of 50% each of the prior year's liability, due 31 January (with the balancing payment for the prior year) and 31 July. A balancing payment trues up on the next 31 January. New sole traders typically face an unexpectedly large payment in their second-year January because the first year's balancing payment plus the first 50% on-account all hit at once.
MTD for Income Tax Self-Assessment (ITSA) starts 6 April 2026 for sole traders and landlords with combined income above £50,000. The £30,000 threshold follows on 6 April 2027. MTD-mandated businesses must keep digital records and submit quarterly updates to HMRC plus an end-of-period statement, then the final tax return. HelloBooks is MTD-ready and will support both the quarterly submissions and the final SA100 + supplementary pages.
Questions UK freelancers & sole traders ask
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