How to Invoice as a Self-Employed Tradesperson in the UK

Invoicing is one of those parts of running a trade business that gets learned by accident — usually after a customer disputes a bill, an accountant flags something on your Self Assessment, or HMRC pings a letter about an unusual VAT line. This guide is the version you wish you had on day one of going self-employed: what UK law actually requires on a valid invoice, how to handle the trade-specific edge cases (VAT, CIS, reverse charge), and how to set up an invoicing flow that gets you paid faster without taking an hour per job.

What HMRC requires on every UK invoice

There are seven fields that must appear on every invoice you issue. Miss any of them and the invoice may not stand up as a valid record for tax purposes — and a customer can legally withhold payment on an invalid invoice.

1. A unique, sequential invoice number. No gaps, no resets mid-year. INV-2026-001, INV-2026-002, etc. The number must be unique and ascending; HMRC explicitly requires you to be able to demonstrate that numbering is consistent across the tax year.
2. Your full business name and address. If you trade under a business name that's different from your own legal name, HMRC requires both — your own name has to appear somewhere on the document.
3. Your customer's full name and address. For business customers, the registered company name and registered office. For domestic customers, the property address is usually enough.
4. The date the invoice was issued (the 'tax point').
5. A clear description of the work done or the goods supplied.
6. The total net amount charged (excluding VAT).
7. If you're VAT-registered: your VAT registration number, the VAT rate applied, and the VAT amount in pounds.

Sequential numbering — the rule most people get wrong

HMRC's sequential-numbering rule is more strict than it sounds. The numbers must be consecutive: if you issue INV-001 and INV-003, you have to be able to show what happened to INV-002 (it was issued and then cancelled, with a credit note? Or it was never issued and you skipped a number?). Skipped numbers without explanation are exactly the kind of thing that triggers a deeper look in an HMRC compliance check.

The simplest pattern, and the one most invoicing software defaults to, is YEAR-SEQUENCE: INV-2026-001, INV-2026-002, etc., resetting at 001 each new tax year. It's easy to verify at a glance and easy to defend. Avoid date-based numbering (INV-260511-001 etc.) — it's brittle when you issue multiple invoices in a day, and the sequence isn't obviously consecutive.

VAT — when to charge it, and how to show it

The VAT registration threshold for 2026/27 is £90,000 of taxable turnover in any rolling 12-month period. Below the threshold, registration is voluntary. Above it, registration is compulsory within 30 days of crossing the line.

If you're VAT-registered, every invoice needs three additional fields beyond the seven above:

• Your VAT registration number (printed in the header or footer).
• The VAT rate applied to each line item. Most domestic plumbing, electrical and decorating work is standard-rated 20%. Specific reduced-rate work (renovation of homes empty 2+ years, conversions of non-residential to residential) is 5%. Zero-rated work (new builds, some disability adaptations) is 0%. Any line that doesn't fit standard rate needs a brief justification on the invoice.
• The VAT amount in pounds, separately from the net amount. The customer needs to see both the net subtotal and the VAT line so they can reclaim VAT correctly if they're VAT-registered themselves.

CIS — the construction-specific layer

If you work as a subcontractor under the Construction Industry Scheme (CIS) — common on new-build sites, commercial fit-outs, and any project where a main contractor pays you to do part of the work — your invoicing changes meaningfully. CIS is HMRC's mechanism to make sure subcontractors actually pay their tax: the main contractor deducts a percentage from your labour and pays it directly to HMRC on your behalf, and you reconcile the deduction when you file your tax return.

The deduction rate depends on your CIS registration status:

• Registered under CIS: 20% deducted from labour only.
• Not registered: 30% deducted from labour only.
• Gross-payment status (only available to high-turnover subcontractors who meet HMRC's compliance tests): 0% deducted.

Crucially, CIS deductions apply to labour only — materials are excluded. So a CIS invoice must clearly separate the labour total from the materials total, then apply the deduction to the labour figure, then show the net amount payable. A typical CIS invoice structure:

1. Line items for labour and materials, broken out separately.
2. Subtotal of labour: £X
3. Subtotal of materials: £Y
4. Net total before CIS: £X + £Y
5. CIS deduction (20% of labour only): -£0.20 × X
6. Net amount payable: total - deduction

Reverse-charge VAT — the trap for VAT-registered subcontractors

Since March 2021, the VAT rules for construction services changed for B2B work between VAT-registered companies. The reverse-charge mechanism means that if you're VAT-registered and supplying construction services to another VAT-registered customer who is themselves under CIS, you don't charge VAT on the invoice — the customer accounts for the VAT themselves through their own VAT return.

On the invoice, this means you still show the VAT calculation (so the customer knows what amount to account for), but you don't add it to the total. Standard wording:

“Reverse charge: Customer to pay the VAT to HMRC. VAT @ 20% on labour: £X (not charged on this invoice).”

The reverse charge applies when all three of these are true: you and the customer are both VAT-registered, the work falls within CIS scope, and the customer is not the 'end user' (i.e. they're going to invoice it on to someone else). If the end customer is the homeowner or building owner, standard VAT applies — not reverse charge.

Late payment terms — how to put a legal floor under your invoices

Under the Late Payment of Commercial Debts (Interest) Act 1998, all UK businesses have a statutory right to charge interest and recover collection costs on overdue commercial invoices. The default is 8% + Bank of England base rate, plus a fixed compensation (£40 for invoices under £1,000; £70 between £1,000–£9,999; £100 over £10,000).

You don't have to put this on your invoice — the right exists by statute. But spelling it out clearly tends to reduce disputes, because customers see you know your rights. Standard wording:

“Payment due within 30 days of invoice date. Late payments may attract interest at 8% + Bank of England base rate under the Late Payment of Commercial Debts (Interest) Act 1998, plus statutory compensation.”

How to actually get paid faster

The single biggest predictor of whether an invoice gets paid quickly isn't the invoice format — it's the time between finishing the work and sending the invoice. Tradies who invoice within 24 hours of the job (ideally same-day, from the van) consistently get paid 30–50% faster than tradies who batch their invoicing on a Sunday evening. Customers' memory of the work is freshest in the first day; their willingness to pay drops sharply after a week.

Same-day invoicing is the reason WhatsApp-native invoicing tools like Wedge exist. The tradie messages "Invoice Sarah Patel £180 for EICR plus £450 for remedials" from the van; the AI generates the invoice, applies your registration numbers, sequential numbering, VAT, CIS deductions where flagged, attaches your bank details and a Stripe payment link, and sends it to Sarah on WhatsApp. Customer pays in WhatsApp; reminders go automatically if they don't.

A practical end-to-end example

A NICEIC-registered electrician finishes an EICR plus remedials in West London. Customer is a private landlord with one property. The invoice should show:

• Business name and address (electrician's), NICEIC registration number in the header.
• Landlord's name and the property address.
• Today's date, invoice number INV-2026-014, due date 30 days out.
• Line items: EICR — £180; First fix remedial — £290; Consumer unit replacement — £450; Materials (parts) — £120. Subtotal £1,040.
• VAT line if registered: 20% on £1,040 = £208. Gross total £1,248. If reverse charge applies: VAT shown as a note, total stays at £1,040.
• Bank details: sort code, account number, reference.
• Payment terms with the Late Payment Act wording.

Total time on a properly-built invoicing tool: about 60 seconds. Manual on a template: 15–20 minutes. Multiply by 5 invoices a week and the difference compounds into a couple of working days per year.

What good invoicing looks like

• Sequential numbering with no gaps. INV-2026-001, INV-2026-002.
• All seven HMRC fields present on every invoice. Your trade qualification numbers (Gas Safe, NICEIC, Part P) in the header.
• VAT, CIS, and reverse-charge logic correct for each customer.
• Materials and labour broken out as separate line items — customers stop questioning the total when they can see exactly what it covers.
• Bank details on every invoice. Free bank transfer is always faster than card payment.
• Late payment terms in the footer.
• Sent same-day, from the van.

Get those right and the actual invoicing part of running a trade business stops being a Sunday-evening chore. Tools like Wedge automate every line of this from a WhatsApp message; templates like our free UK invoice template give you the same structure to fill in by hand.