You've wrapped up a big flooring job, packed the kit, and your phone's buzzing for the next site. But before you move on, there's one thing standing between you and getting paid—your invoice.
For the average UK SME, late payments add up to £22,000 owed at any one time, and the longer you wait to send that invoice, the more likely it is to join the pile. The faster you get it out, the sooner the money lands in your account.
Knowing how to write an invoice properly means getting paid faster, avoiding disputes, and keeping your cash flow steady. Most trade businesses lose money simply because their invoices are unclear, incomplete, or sent too late.
In this guide, you'll learn exactly how to write an invoice step-by-step, what details to include, and how to speed things up with an invoicing tool like Intrflex.
Why Writing a Clear Invoice Matters for Trades
Getting your invoice right directly affects how quickly you get paid and how smoothly your business runs.
Get Paid Faster
Clear invoices make it simple for customers to pay quickly. When all the payment details are right there, customers don't need to dig around for information or wait to ask questions. No need to chase them up or send endless reminders.
A tidy, clear invoice shows you've got your act together. Plus, it makes customers more likely to pay on time. Customers are more likely to prioritise paying invoices that look organised and complete.
Faster payouts make your cash flow steady, so you can cover materials and wages without stress. When payment comes in faster, you're not fronting money for the next job or waiting weeks to pay your team.
Fewer Payment Delays
All the payment details are included upfront, so customers know exactly how to pay and when it's due. They don't have to ask for extra info before paying, which cuts down on back-and-forth emails or calls that slow payment.
Late payments tend to happen because something's missing from the invoice, like payment terms, due date, or bank details. A fully sorted invoice means there's no room for excuses.
Better Records for Tax Purposes
Detailed invoices keep your accounts accurate and help track what's been paid. If you're VAT registered or a limited company, get your invoices right so HMRC doesn't come knocking.
It also makes it easier for your accountant to file taxes without missing claims or information. Good invoice records cover your back during tax inspections or if customers dispute charges later.
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Book a demoFewer Disputes
Everything is written down in black and white, so there's no confusion over what was agreed or charged. When services provided and costs are clearly listed, customers understand exactly what they're paying for.
This covers your back if anyone kicks up about the bill later on. A detailed invoice shows the work done, when it was completed, and what was agreed upfront.
Step-by-Step – How to Write an Invoice That Gets You Paid Faster
Here's how to write an invoice that's complete, clear, and quick to send.
1. Add Your Business Details
Start with your business name—your trading name or company name as it appears on official documents. Include your registered office address, especially if you're a limited company, as this is legally required on invoices.
Add your contact details, like phone number and email address, so customers can reach you if needed. Including your company logo makes your invoice look professional and reinforces your brand.
If you're a sole trader, use your business name and business address. For limited company invoices, include your company registration number to meet legal requirements.
2. Include the Customer's Details
Write the customer's company name or individual's name exactly as they've given it to you. For larger businesses, include a contact person so the invoice reaches the right department.
Add their business address where the invoice should be sent. Check the details twice so your payment doesn't disappear into the wrong account.
Getting customer details right prevents confusion and shows attention to detail that customers appreciate.
3. Give the Invoice a Unique Number
A sequential invoice number makes it easy to track invoices issued and helps with your accounting system. Start with 001 and work up, or use a system that includes the year, like 2025-001.
Unique invoice numbers help avoid duplicate records and make it easier to reference specific invoices when customers call. This also helps if you need to chase late payments or handle disputes.
4. Set the Invoice Date and Supply Date
The invoice date shows when you're issuing it, while the supply date shows when goods or services were delivered. Both dates help avoid confusion and late payments.
If you completed work over several days, use the completion date as your supply date. For ongoing projects, be clear about which period the invoice covers.
These dates are important for VAT purposes and help customers understand when payment terms start running from.
5. Add a Clear Description of Services Provided
Use a short, clear, brief description that explains exactly what you did. For example, put "floor sanding and sealing" rather than just "labour." List all services rendered with costs for each line item.
Being specific helps customers understand what they're paying for and reduces questions. Include materials used if they're charged separately from labour costs.
This makes it clear what the customer owes and shows the value they've received. Clear descriptions also help if you need to reference the work later for warranty or repeat jobs.
Good descriptions cover you if payment disputes arise and help customers justify expenses to their own accounting teams. For more guidance on accurate job tracking, see our guide on payroll precision.
6. Show the Total Amount and VAT if Applicable
Display the total amount clearly. The "grand total" the customer needs to pay. If you're VAT registered, add applicable sales tax to create a proper VAT invoice with VAT shown separately.
State clearly if you're VAT registered and include your VAT number on the invoice. For sole trader invoices, indicate if VAT isn't applicable.
Show what's labour, what's materials, and what's VAT so there's no eyebrow-raising over the total. This transparency helps with their own accounting and reduces questions about pricing.
For guidance on pricing structure, check our article on flat rate vs hourly pricing.
7. State Payment Terms and Due Date
Set clear payment terms like 7, 14, or 30 days from the invoice date. Clearly state the due date so there's no confusion about when payment is expected.
If you charge late fees, say what they are and when they start, so there's no surprise. It gets you paid on time and keeps the cash moving.
Common payment terms help set expectations, but adjust them based on your relationship with the customer and industry standards.
8. List Accepted Payment Methods and Bank Details
Include all accepted payment methods, like bank transfer, debit card, cash, or multiple payment options. Give customers payment options so they can pay you sharpish.
Stick your bank details on there (e.g., account number, sort code), so they can't say they didn't know how to pay. Double-check these details to avoid payment delays.
The more payment options you give, the faster customers can pay. Consider online payment options to speed up the process even more.
9. Add Any Purchase Order Number if Needed
Include the purchase order number if your customer provided one—this is essential for some commercial contracts. It helps match your invoice to their internal order system.
Large companies typically can't process invoices without matching purchase order numbers, so don't skip this step for commercial work.
10. Send Reminders and Follow Up if Needed
Even with clear terms, late payments happen. Use automated payment reminders in your invoicing software to save time chasing payments.
A friendly follow-up call or email can resolve payment issues quickly. Sometimes payments get delayed for simple reasons like invoices getting lost in email or needing approval from someone who's been away.
This keeps money moving and saves you a load of boring admin. Following up professionally maintains good customer relationships while keeping your business running smoothly.
How to Send Invoices Properly
How you send your invoice affects how quickly it gets processed and paid.
Choosing the Right Subject Line for Invoice Emails
Keep your subject line clear with all the key details. For example, "Invoice #045 – Beaver Floor Care – £850 – Due 15/09/25," the invoice provides the recipient with everything they need to know at a glance.
A clear subject line makes it easier for your client to spot and action the invoice in their inbox. Vague subject lines typically get overlooked or deleted by mistake.
Include your business name, invoice number, amount, and due date in the subject line for maximum clarity.
Using an Invoice Email Template
Use an invoice email template to save time and keep your communications consistent. Always include a polite request for payment line that's professional but clear about expectations.
Template emails also help you send professional invoices without having to write from scratch each time. Standard wording also reduces the chance of saying something that delays payment.
If using software like Intrflex, set automated payment reminders to go out before the due date. This keeps payments on track without you having to remember to follow up manually.
How to Speed Up the Invoicing Process With Intrflex
If you're still manually typing out invoices in Word, you're wasting hours every month.
Our invoicing tool lets you create invoices on-site or in the office with all your details pre-filled. Turn quotes into invoices instantly without re-entering customer information or job details.
Send professional invoices with consistent formatting and all required details included automatically. Track who's paid and send reminders automatically so you don't have to chase payments manually.
The system handles recurring invoices for maintenance contracts and lets you give multiple payment options to speed up payments. Digital invoices get delivered instantly and can be paid online for faster cash flow.
Reduce admin time so you can focus on jobs that bring in money rather than paperwork. Try Intrflex's invoicing tool to see how quickly you can go from finished job to invoice sent.
Common Mistakes to Avoid When You Write an Invoice
Even experienced tradespeople can make these common invoicing mistakes—here's how to avoid them.
Missing contact details or wrong company details slow down payment and make you look unprofessional. Always double-check customer information before sending.
Forgetting the invoice number or due date creates confusion and gives customers an excuse for late payment. These details should be prominent on every invoice.
Not listing accepted payment methods forces customers to contact you before they can pay, adding delays. Make payment as easy as possible by including all the options up front.
Being too vague with services provided or services rendered leads to questions and potential disputes. Be specific about what work was completed and when.
Quick Invoice Checklist for Trades
Before you hit send, run through this quick checklist to make sure you've included everything:
- Business name/company name
- Registered office address/business address
- Contact details (phone, email)
- Customer's company and contact person
- Invoice number
- Invoice date and supply date
- Brief description of services provided
- Total amount and applicable sales tax
- Payment terms and due date
- Accepted payment methods and bank details
- Purchase order number (if applicable)
This checklist helps ensure you don't miss critical information that could delay payment or create confusion.
Send Invoices that Keep Cash Flowing
A solid invoice helps you get paid on time, keeps your records straight, and saves you from chasing customers. Make sure it shows all the essentials, like your business details, invoice number, payment terms, due date, and how you want to be paid.
Be clear about the work you've done and the total amount owed so there's no room for doubt. Professional invoices build trust and encourage faster payment from customers.
When you know how to write an invoice properly, you cut payment delays and improve cash flow. The right invoicing software makes this process even faster by automating repetitive tasks and tracking payments.
With Intrflex, you can send an invoice before you’ve even packed the van.
Book a free demo to see how it works in real life.
