How to Invoice as a Self Employed Builder UK 2026

Updated June 2026 · 8 min read · BuilderLog Team

Getting your invoicing right means getting paid faster and keeping HMRC happy. But most self employed builders have never been taught what an invoice should actually look like — especially when CIS is involved. This guide covers exactly what to include, how to handle the CIS split, and how to chase payment without being awkward about it.

What every builder invoice must include

HMRC doesn’t prescribe a specific invoice format for sole traders, but a professional invoice should include:

• Your name and business name (if different)
• Your address
• Your CSCS card number (if applicable)
• Your UTR number (some contractors require this)
• The customer’s name and address
• A unique invoice number (just count upwards — INV001, INV002, etc.)
• The date
• A clear description of the work done
• The total amount due
• Your payment terms (e.g. “Payment due within 14 days”)
• Your bank details for payment

CIS invoices — separating labour and materials

If you’re working as a CIS subcontractor, your invoice format matters even more. The contractor needs to separate your payment into labour and materials because CIS deductions only apply to the labour portion. Materials are always paid in full.

Your CIS invoice should clearly show:

Line item	Amount
Labour — kitchen extension groundwork (5 days × £220)	£1,100
Materials — concrete, rebar, membrane	£450
Gross total	£1,550
Less CIS deduction (20% of £1,100 labour)	-£220
Net payment due	£1,330

Direct customer invoices — no CIS

When you’re working directly for a homeowner (not a contractor), CIS doesn’t apply. Your invoice is simpler — just the total amount due with a clear breakdown of what you did.

A good domestic invoice includes a brief description of each stage of work, any materials you supplied and are charging for, and the total. Customers appreciate transparency — they’re more likely to pay quickly when they can see exactly what they’re paying for.

Payment terms — what works

For domestic customers: “Payment due on completion” or “Payment due within 7 days” is standard. For larger jobs, staged payments are normal — 25% deposit, 50% at midpoint, 25% on completion. Never start a big job without a deposit.

For CIS subcontract work: Contractors typically pay monthly, within 14 days of receiving your invoice. Your contract or agreement should specify the payment terms. If it doesn’t, 30 days is the legal default under the Late Payment of Commercial Debts Act.

For late payers: You’re legally entitled to charge interest on late commercial payments (8% + Bank of England base rate). In practice, a polite reminder at 7 days overdue and a firmer one at 14 days works better than threatening legal action. But knowing you have the right to charge interest gives you leverage.

How to get paid faster

Invoice immediately. Don’t wait until the end of the week or the end of the month. Invoice the same day you finish the work, while the customer is still happy with what you’ve done.

Make it easy to pay. Include your bank details on every invoice. Better yet, include a QR code for bank transfer. The fewer steps between receiving the invoice and paying it, the faster you get paid.

Send a professional invoice, not a text message. A proper invoice with your name, CSCS number, and a clear breakdown looks professional and gets taken seriously. A WhatsApp message saying “that’ll be £800 mate” does not.

Chase promptly. If payment is overdue by more than 7 days, send a reminder. Most late payments aren’t deliberate — the customer just forgot or lost the invoice. A polite nudge fixes it 90% of the time.

Generating invoices on site

Apps like BuilderLog let you generate a professional PDF invoice on your phone while you’re still on site. Your name, CSCS number, the job details, and the price are all pulled from the job record — tap one button and it’s ready to print, save, or email. No templates, no spreadsheets, no going home and typing it up later.

VAT — do you need to charge it?

You only need to charge VAT if your turnover exceeds £90,000 (the 2026/27 threshold). Below that, you’re not VAT-registered and your invoices should not include VAT. If you’re above the threshold and VAT-registered, your invoices must show your VAT number, the VAT rate, the VAT amount, and the total including VAT.

If you’re working as a CIS subcontractor and you’re VAT-registered, the domestic reverse charge applies to most business-to-business construction supplies. Under this, you don’t charge VAT on your invoice — the contractor accounts for it instead. This only applies when both parties are VAT-registered and CIS-registered. If you’re not VAT-registered, ignore this entirely.

Keeping records of your invoices

HMRC requires you to keep copies of all invoices issued for at least 5 years after the 31 January submission deadline for the relevant tax year. That means invoices from the 2026/27 tax year (return due January 2028) must be kept until at least January 2033.

Digital copies are perfectly acceptable — you don’t need to keep paper. Save a PDF of every invoice you send, ideally in a named folder (e.g. “Invoices 2026-27”). Apps like BuilderLog store your invoice history automatically, so you always have a record of what you sent and when.

What to do when a customer won’t pay

It happens to every builder eventually. You’ve done the work, sent the invoice, chased twice, and they’re still not paying. Here’s the escalation path:

Day 1-7: Send the invoice, wait.

Day 8: Polite reminder by text or email. “Hi, just checking you received my invoice dated [date] for £[amount]. Happy to answer any questions.”

Day 15: Firmer follow-up. “This invoice is now overdue. Please arrange payment within 7 days.”

Day 22: Final notice. “If payment is not received within 7 days, I will need to consider further action including statutory interest charges.”

Day 30+: Letter before action (you can download templates from gov.uk). If that doesn’t work, small claims court via Money Claims Online — costs £35-£115 depending on the amount and can be done without a solicitor.

Most payment disputes never reach court. A formal letter before action resolves the majority of cases because the customer realises you’re serious.