If you have just started freelancing or set up as a sole trader in the UK, invoicing correctly from the start saves you trouble with clients, with HMRC, and with your own bookkeeping. The rules are simpler than most people expect. Specific fields have to appear on every invoice, and the requirements differ depending on whether you are VAT-registered.
A sole trader is the simplest business structure in the UK. You are self-employed, running the business as an individual, personally liable for its debts, and reporting income and expenses through Self Assessment each year. Unlike a limited company, there is no legal separation between you and the business.
You can trade under your own name or a business name. A business name still has to connect back to your real name on formal documents, invoices included. "Jane Smith trading as JS Consulting" works, and so does "Jane Smith". A business name that hides who you actually are does not.
Below the £90,000 VAT registration threshold you do not have to register for VAT, charge it, or put a VAT number on your invoices. Six pieces of information still have to be there for the invoice to be legally valid:
That is the whole list. No VAT, no tax point date, no registration number. A clean document carrying those six fields is a valid UK invoice for a non-VAT-registered sole trader.
One common mistake: adding a "VAT: £0.00" line because it looks more professional. It does the opposite. A £0.00 VAT line makes clients think you are VAT-registered, or that there is VAT for them to reclaim. If you are not registered, leave VAT off the invoice entirely. The Invoice Maker handles this properly. Leave the VAT field blank and the row does not appear in the PDF.
Once your taxable turnover passes £90,000 in any rolling 12-month period, you must register for VAT with HMRC within 30 days of the end of the month in which you crossed it. After that you charge VAT on your invoices and file quarterly VAT returns through Making Tax Digital compatible software.
Registering voluntarily below the threshold is also an option, and it makes sense when most of your clients are VAT-registered businesses who reclaim the VAT anyway and you want to reclaim VAT on your own purchases.
Once you are registered, your invoices need nine specific fields. Miss one and the invoice is invalid for VAT purposes: your client cannot reclaim the VAT, and HMRC can raise queries at a VAT inspection.
The Invoice Maker has fields for all nine. For services invoiced at a single rate, the tax point date is usually the invoice date. Enter your VAT registration number in the business details section and it appears on the PDF in the right position.
HMRC wants invoice numbers sequential and unique. You cannot reuse a number and you cannot leave gaps. Start at 001 or INV-001 and add one each time. If you prefer a year prefix, INV-2026-001, reset the counter at the start of each financial year.
Never delete an invoice. If you spot an error on one you have already sent, issue a credit note referencing the original invoice number, then issue a corrected invoice under a new number. That keeps the audit trail intact.
Payment terms say when payment is due and what happens when it is late. UK freelancers mostly use net 14 or net 30. For a new client, net 7 or net 14 shortens the gap between finishing the work and seeing the money.
The Late Payment of Commercial Debts (Interest) Act 1998 is a statutory right most UK freelancers never exercise. It entitles you to statutory interest of 8% above the Bank of England base rate on overdue business-to-business invoices, plus a fixed debt recovery charge of £40, £70, or £100 depending on the invoice amount. No contract clause is needed. It applies automatically to B2B transactions.
A single line in the invoice notes, "Statutory interest will apply to overdue invoices under the Late Payment of Commercial Debts (Interest) Act 1998", is accurate and a polite deterrent at once. The UK Late Payment Calculator works out what you can claim on any overdue invoice.
The Invoice Maker builds HMRC-compliant invoices in your browser with no account, no monthly fee, and no watermark:
Export the invoice as JSON to keep a reusable template. Next time, reimport it, change the invoice number and date, and download, without retyping your business details or the client's.
HMRC requires sole traders to keep records of all income and expenses for at least five years and ten months after the end of the tax year they relate to. Most accountants suggest six years to be safe. For invoices that means keeping a copy of every one you issue, as a PDF in a folder, in cloud storage, or inside your accounting software.
On your Self Assessment return you report total income, meaning all invoices issued and paid, and your allowable business expenses. Income tax is due on the profit, which is income minus expenses. National Insurance is due as well: Class 2 at a flat rate and Class 4 as a percentage of profits above the threshold.
Sequential numbering, the required HMRC fields, clear payment terms, and a copy of every invoice are the habits that make Self Assessment and VAT inspections uneventful.