Self-Employed Invoicing Checklist UK (2026): What Every Invoice Must Include

Most sole traders lose time — or get paid late — because their invoices are missing something a client's accounts team needs. This checklist covers exactly what a UK invoice must include, plus the VAT and payment-terms rules that catch people out. When you're ready, FairInvoice's free generator builds a compliant invoice in under a minute — free, no sign-up.

The essentials every invoice needs

• Your name (or business name) and trading address
• The client's name and address
• A unique, sequential invoice number (e.g. INV001, INV002, or a year-based format like 2026-001) — no gaps, no repeats
• The invoice date, and the supply date if it's different
• A clear description of the goods or services provided
• The total amount charged

Sole trader specifics

As a sole trader you should show both your personal name and any trading name you use, plus a correspondence address (this can be your home address) where paperwork can legally reach you.

Do you need to charge VAT?

You must only add VAT to an invoice if you're VAT-registered. The UK VAT registration threshold is £90,000 of taxable turnover in a 12-month period (2025/26 threshold) — below that, unless you've registered voluntarily, your invoice must not include VAT. Once registered, the standard VAT rate is 20%, and a VAT invoice must show your VAT registration number, the tax point (supply date), the net amount, the VAT rate, and the total VAT charged in sterling.

See our guide to VAT registration for sole traders for the full registration rules and deadlines.

Invoice numbering rules

Each invoice needs a unique, sequential number with no gaps or repeats — inconsistent numbering is a red flag in an HMRC check. Cancelled invoices should keep their number in your records rather than being reused. FairInvoice's paid tier can auto-number these for you; the free tier works fine if you're numbering manually.

More detail in our guide to UK invoice numbering rules.

Payment terms & late payment

If you and your client haven't agreed payment terms, the legal default is 30 days from the invoice or delivery date, whichever is later. You also have a statutory right to charge interest on qualifying late commercial payments under the Late Payment of Commercial Debts Act — worth stating your terms clearly on the invoice itself (e.g. "Payment due within 14 days") so there's no ambiguity.

Record-keeping

Keep copies of every invoice you send (and receive) for at least 5 years after the 31 January filing deadline of the relevant tax year — HMRC can ask to see them.

A worked example

Here's a compliant invoice for a sole trader plumber who isn't VAT-registered (turnover below £90,000, so no VAT is shown).

The easy way to tick every box

Build your own compliant invoice free at FairInvoice — no account, no watermark, download as a PDF in under a minute.

This guide is general guidance, not tax or legal advice. Rates, thresholds and rules can change — verify anything that matters against GOV.UK or an accountant before relying on it.