You are currently viewing How to Invoice Clients as a Sole Trader UK

How to Invoice Clients as a Sole Trader UK

Invoicing correctly as a sole trader protects your cash flow, keeps HMRC happy and makes you look professional to clients. This guide covers everything you need to know, from what must appear on every invoice to how VAT fits in, how to chase late payments and how your invoices tie into your self assessment tax return.

What is a sole trader invoice?

An invoice is a formal request for payment. It tells your client what work you completed, what they owe and when they need to pay. As a sole trader, your invoices are also financial records, HMRC expects you to keep them as part of your business accounts.

There is no single prescribed template you must use. A plain Word document, a spreadsheet or dedicated software all work, provided the invoice contains the right information. What matters is the content, not the format.

What must be on an invoice?

HMRC sets out the information that must appear on every invoice you issue. Miss any of these and you could create headaches, both for your client’s accounts and your own records.

Mandatory details for sole trader invoices

  • The word “Invoice”: clearly at the top of the document.
  • A unique invoice number: sequential numbering keeps your records tidy and is a legal requirement.
  • Your name and address: your full legal name (the name you trade under) and a business or home address.
  • Your client’s name and address: the full name or company name of the person or business you are billing.
  • The invoice date: the date the invoice is issued.
  • A description of the goods or services: enough detail so the client knows exactly what they are paying for.
  • The amount charged: broken down per item or service where applicable.
  • The total amount due: clearly stated, with or without VAT as appropriate.

If you are VAT-registered, additional details are required, covered in the next section.

Optional but recommended details

  • Your payment due date or payment terms (e.g. “Payment due within 30 days”).
  • Your bank account details (sort code and account number) to make paying straightforward.
  • A purchase order number if your client has provided one, many larger businesses require this before they will process a payment.
  • Your email address and phone number for any queries.

If you trade under a business name rather than your own name, you still need to include your personal name somewhere on the invoice. For example: “Jane Bloggs trading as JB Design.”

VAT invoices, when and how

Most sole traders start out not VAT-registered. If your taxable turnover stays below the VAT registration threshold, £90,000 in 2026/27, you do not need to charge VAT and you do not need to issue VAT invoices. Simply issue a standard invoice for the amount agreed.

Once your turnover exceeds £90,000 in a rolling 12-month period, you must register for VAT with HMRC. From that point, every invoice to a VAT-registered business must be a full VAT invoice. VAT invoices need everything in the standard list above, plus:

  • Your VAT registration number.
  • The tax point (usually the invoice date or the date of supply, whichever comes first).
  • The VAT rate applied to each line item.
  • The net amount (excluding VAT) per line.
  • The total VAT charged.
  • The gross total (net + VAT).

If you are selling to non-VAT-registered individuals (the general public), a simplified VAT invoice is acceptable for sales under £250, this can omit the customer’s details and some of the line-level breakdown. For most business-to-business invoicing, use a full VAT invoice every time.

NDCA handles VAT returns for sole traders who need support with compliance once they register.

Invoice numbering and record keeping

Every invoice you issue needs a unique sequential number. You can use a simple number sequence starting at 001, or you can include a year prefix such as 2526-001 to make filing easier. What you cannot do is skip numbers, reuse numbers or issue two invoices with the same number.

HMRC requires sole traders to keep records of all invoices for at least five years after the 31 January submission deadline for the relevant tax year. In practice, many accountants recommend keeping them for six years. Store copies digitally or in paper form, both are acceptable right now, though Making Tax Digital for Income Tax (MTD ITSA) will change digital record-keeping requirements from April 2026 for self-employed people and landlords with income over £50,000.

Good invoice records feed directly into your bookkeeping, making it far quicker to prepare your year-end accounts and self assessment return.

Setting payment terms

Payment terms tell the client when you expect to be paid. If you do not set them, you are leaving yourself open to slow payment with no clear recourse.

Common payment terms

  • Due on receipt: payment expected as soon as the invoice is received. Useful for one-off jobs or new clients.
  • Net 14: payment due within 14 days.
  • Net 30: payment due within 30 days. The most common in the UK.
  • Net 60: 60 days. Frequently used by larger businesses but can damage your cash flow significantly.

The Late Payment of Commercial Debts (Interest) Act 1998 gives you the right to charge statutory interest on overdue business-to-business invoices. The statutory rate is 8% above the Bank of England base rate. The Bank of England publishes the current base rate on its website. You can also charge a fixed debt recovery fee (£40, £70 or £100 depending on the invoice value). This right exists automatically, you do not need to state it on your invoice, though doing so does remind clients that late payment has consequences.

State your payment terms clearly on every invoice, and agree them with clients before you start work. Do not let payment terms be an afterthought in your contract.

How to get paid faster

Getting paid on time is one of the biggest practical challenges for sole traders. These approaches make a real difference.

Ask for a deposit upfront

For any project over a certain value, ask for a deposit, typically 25% to 50%, before you start work. This reduces your risk and filters out clients who are not serious.

Invoice promptly

Send the invoice as soon as the work is done, or on the agreed billing date. The sooner the clock starts on your payment terms, the sooner you get paid. Delaying your own invoice is the most common self-inflicted cash flow problem.

Make payment easy

Include your bank details on every invoice. Consider adding a payment link through a service like Stripe or PayPal if your clients prefer to pay by card. Fewer steps to payment means faster payment.

Follow up systematically

Send a polite reminder a few days before the due date, on the due date if payment has not arrived, and then again shortly after. Keep a tone that is professional, most late payments are down to oversight rather than bad faith.

Use milestone billing for longer projects

If you are working on a project that runs over several weeks or months, break the billing into milestones. Invoice at the end of each phase rather than waiting until the entire project is complete. This protects your cash flow and gives you leverage if a client becomes difficult.

Invoicing software for sole traders

You do not need expensive software to invoice clients. A well-structured Word template or spreadsheet works perfectly well when you are starting out. As your client list grows, dedicated software saves time and reduces errors.

Popular options for UK sole traders include:

  • Xero: cloud accounting software that handles invoicing, VAT, bank reconciliation and reporting. Our bookkeeping service can set it up properly for you.
  • FreeAgent: popular with freelancers and contractors. Handles self assessment filing directly from the software.
  • QuickBooks: solid all-round option with good invoicing features.
  • Wave: free at the core level, suitable for very small sole traders with straightforward needs.

Whichever tool you choose, the key benefit is that your invoice data feeds directly into your accounts, cutting the admin time at year-end and making MTD compliance simpler when the rules apply to you.

How invoices affect your tax

As a sole trader, you pay Income Tax and National Insurance on your profits, not your turnover. Profits are your total income minus your allowable business expenses. Your invoices represent your income, so keeping accurate records of every invoice you raise is the foundation of your tax calculation.

Cash basis vs accruals basis

The cash basis means you record income when you actually receive payment, and expenses when you actually pay them. The accruals basis means you record income when the invoice is issued, regardless of when money hits your account.

Most sole traders use the cash basis because it is simpler. From April 2024, the cash basis became the default for sole traders unless you actively opt out. If you have a lot of outstanding debtors or creditors at your year-end, your accountant can advise which basis suits you better.

What income do you declare?

Every invoice you raise is potential income. On your self assessment tax return, you report your total business income and total allowable expenses. The difference is your taxable profit. In 2026/27, you pay no Income Tax on the first £12,570 (your personal allowance), 20% on profits from £12,571 to £50,270, 40% on profits from £50,271 to £125,140 and 45% above that.

Keep your invoices organised throughout the year

Waiting until January to sort through 12 months of invoices is painful and error-prone. Set aside time each month to reconcile what you have invoiced, what has been paid and what is outstanding. Good monthly habits make January far less stressful.

Common invoicing mistakes to avoid

Not keeping copies

Always retain a copy of every invoice you send, whether digital or paper. If HMRC ever queries your income, you need to be able to produce your records.

Forgetting to include all required details

A missing invoice number or address can cause problems for your client’s accounts department and delay payment. Use a template that prompts you to complete every field.

Mixing personal and business finances

Open a separate bank account for your business income and expenses, even as a sole trader. It makes bookkeeping far simpler and demonstrates a clear separation of finances to HMRC if asked.

Not agreeing terms before starting work

If there is no agreement upfront about price, scope and payment terms, disputes become much harder to resolve. A simple written agreement or even a clear email exchange protects both you and your client.

Ignoring late payments

Letting overdue invoices slide sets a precedent. Chase promptly, professionally and consistently. If a debt becomes genuinely difficult to recover, consider using a statutory demand or a debt recovery service, but this should be a last resort after clear communication has failed.

Issuing invoices without a VAT number when VAT-registered

Once you are VAT-registered, every business-to-business invoice must show your VAT number. Omitting it is a compliance failure and can cause your client difficulties when they try to reclaim the VAT.

Frequently asked questions

Does a sole trader have to use the word “Invoice” on their documents?

Yes. The word “Invoice” must appear clearly on the document. HMRC requires this to distinguish invoices from quotes, estimates or receipts. It also helps your clients’ accounts teams process the payment correctly.

Can I invoice before I complete the work?

Yes. You can issue a pro-forma invoice or request a deposit before work begins. A pro-forma is not a VAT invoice and should be marked as such. Once the work is complete, issue a final invoice for the balance. If you are asking for full payment upfront, a standard invoice is fine as long as the supply date is clear.

Do I need to register for VAT as a sole trader?

Only if your taxable turnover in a rolling 12-month period exceeds £90,000 (the 2026/27 threshold). Below that, VAT registration is optional. Some sole traders register voluntarily if most of their clients are VAT-registered businesses, as they can then reclaim VAT on their own purchases.

What happens if I do not issue invoices?

Without invoices, you have no formal record of the income you have earned or the payment terms you set. This creates problems with self assessment, makes it very hard to chase late payment and leaves you exposed if HMRC investigates your business. Always invoice for every piece of work.

How long should I keep my invoices?

Five years from the 31 January filing date for the relevant tax year is the minimum. In practice, keeping records for six years is safer. Store them digitally or in paper form, both are currently acceptable.

Can I send invoices by email?

Yes. Email is the most common method and is fully acceptable to HMRC. Send the invoice as a PDF to prevent the formatting being altered. Keep a copy of the sent email and the invoice file in your records.