How to Write an Invoice: Step-by-Step Guide

Writing an invoice might seem straightforward, but getting it right makes the difference between prompt payment and chasing clients for weeks. Here's a step-by-step guide to writing invoices that get you paid.

Step 1: Add Your Business Information

Start with your business details at the top of the invoice. Include your full business name (or trading name), address, email address, and phone number. If you're VAT registered, include your VAT number here too.

Step 2: Add Your Client's Details

Include the client's company name, billing address, and contact person. Getting these right is important — especially for larger companies where invoices go through a finance department that may reject invoices addressed incorrectly.

Step 3: Assign an Invoice Number

Every invoice needs a unique identifier. Use a consistent numbering system like INV-001, INV-002 or include the year: 2026-001. This makes it easy to reference invoices in communication and for your own records.

Step 4: Set the Dates

Include two dates: the invoice date (today) and the due date. The due date is critical — without it, clients have no urgency to pay. Common terms are Net 30 (due in 30 days) or Due on Receipt.

Step 5: List Your Line Items

This is the most important section. For each service or product, include:

• A clear description of the work done
• The quantity (hours, units, or days)
• The unit price or hourly rate
• The line total (quantity x price)

Be specific. "Website development — homepage redesign, 15 hours @ £75/hr" is much better than "Web services."

Step 6: Calculate Totals

Show the subtotal, any applicable tax (VAT at 20% in the UK), and the final total. Make the total amount prominent and easy to find.

Step 7: Add Payment Information

Tell your client exactly how to pay you. Include bank details (sort code and account number for UK banks), or a payment link. The easier you make it to pay, the faster you'll get paid.

Step 8: Save as PDF and Send

Always send invoices as PDF files — never as Word documents or in the body of an email. PDFs look professional, can't be accidentally edited, and are easy to download and file.