Invoicing feels straightforward until a client queries something, a payment gets delayed, or your accountant asks why your records are inconsistent. A lot of that friction traces back to invoices that are missing information HMRC actually requires.
This is not about being overly formal. It is about sending invoices that hold up, get paid without confusion, and keep your records clean if you are ever asked to show them.
The basics: what every invoice needs
Whether you are a sole trader, a limited company, or anything in between, HMRC expects invoices to include certain information. Here is what needs to be on every invoice you send:
- A unique invoice number — sequential, with no gaps. If you delete or void an invoice, keep a record of it rather than reusing the number.
- Your business name and address — if you trade under a name different from your own, include both.
- The client’s name and address — the legal name of the person or company you are billing.
- The date the invoice was issued
- A clear description of what you supplied — what you did, or what was delivered. “Consultancy services” is vague; “Brand strategy workshop — 4 hours, 3 June 2026” is not.
- The amount being charged — broken down by item if there are multiple line items.
- The total amount due
That is the floor. If you are VAT-registered, the requirements go further.
Additional requirements if you are VAT-registered
Once you cross the VAT registration threshold (currently £90,000 turnover in a 12-month period), your invoices must also show:
- Your VAT registration number
- The VAT rate applied to each item (e.g. 20% standard, 5% reduced, or 0%)
- The VAT amount charged per item and in total
- The total excluding VAT and the total including VAT
- The tax point (usually the date the goods or services were supplied, if different from the invoice date)
A VAT invoice that is missing any of these is not a valid VAT invoice — which matters because your client cannot reclaim VAT on it.
A note on invoice numbering
Sequential numbering is a legal requirement, not just a best practice. Your invoice numbers need to form an unbroken sequence. HMRC does not specify a format — INV-001, 2026-047, or any other system is fine — but gaps in the sequence can raise questions during a tax investigation.
It is also worth keeping voided or cancelled invoices in your records rather than deleting them. Note them as void with a reason, and move on to the next number.
Payment terms
HMRC does not legally require you to state payment terms on an invoice, but it is strongly advisable. Standard terms in the UK are 30 days from the invoice date. If you want payment sooner (or later), state it clearly: “Payment due within 14 days of invoice date.”
If you charge interest on late payments, you must have communicated this to the client before you can enforce it. The Late Payment of Commercial Debts Act allows you to charge statutory interest of 8% above the Bank of England base rate on overdue B2B invoices — but only if your original terms included it or you have agreed it separately.
What about pro-forma invoices?
A pro-forma is not a tax invoice. It is more like a quote in invoice format — used to request payment before goods or services are delivered. You should not record it in your accounts as income, and your client should not use it to reclaim VAT. Once payment is received and the work is done, follow up with a proper invoice.
Receipts vs invoices
An invoice requests payment. A receipt confirms it was received. They are different documents. If a client asks for a receipt after paying, send a separate document (or mark the invoice as paid and reissue it). Do not conflate the two.
Common mistakes worth avoiding
Sending the same invoice number twice. Usually happens when you create invoices manually and lose track. Sequential numbering systems — even a simple spreadsheet running the numbers — prevent this.
Vague descriptions. “Design work — June” tells nobody anything useful, including you, six months later when you are trying to reconcile accounts. Be specific about what was delivered and when.
No due date. “Payment due on receipt” is legally ambiguous. A specific date removes any excuse for delay.
Wrong client details. If you bill a limited company, bill the company — not the individual you dealt with. If the name on the invoice does not match the name on the bank account, it can complicate things for both sides.
Mixing personal and business finances. If you are a sole trader without a dedicated business account, your invoicing records become your only clear evidence of business income. Keep them tidy.
Getting invoicing right from the start is one of those things that pays off quietly — fewer chased payments, cleaner records at tax time, and no awkward conversations about whether something was actually invoiced or not.
If you want to make sure your invoices always include what they should, Griffio handles the numbering, the layout, and the PDF — so there is one less thing to think about.