The complete freelance invoice guide: what to include and how to get paid

Getting paid is the whole point. Yet invoicing is one of the most common sources of confusion and delay for freelancers — especially when starting out. This guide covers everything you need to send a professional, correct invoice that gets paid on time.

What every freelance invoice must include

A proper invoice isn't just a request for money — it's a legal document. In the UK, HMRC specifies what invoices must contain. Missing any of these elements can cause payment delays or complications at tax time:

• The word "Invoice" clearly at the top
• A unique, sequential invoice number
• The invoice date and payment due date
• Your full name (or business name) and address
• Your UTR number (Unique Taxpayer Reference) — for self-employed individuals
• Your client's name and address
• A clear description of the services provided
• The quantity and unit price for each item
• VAT amount if you are VAT registered (standard rate is 20%)
• The total amount due
• Your payment details — bank account, sort code, or payment link

Invoice numbering — do it right from day one

HMRC requires invoices to be numbered sequentially with no gaps or repeats. A clean system is: INV-YYYY-001 (e.g. INV-2025-001, INV-2025-002). Never reuse numbers, never skip numbers, and never go back and change them.

Payment terms — set them clearly and early

Always state your payment terms on every invoice. Common options:

• Net 7: Payment due within 7 days — good for smaller amounts or new clients
• Net 14: Payment due within 14 days — common for freelancers
• Net 30: Payment due within 30 days — standard for larger projects

Under the Late Payment of Commercial Debts Act, you are legally entitled to charge interest on overdue invoices (currently 8% above the Bank of England base rate) plus a fixed compensation of £40–£100 depending on the invoice amount.

What a well-structured invoice looks like

How to handle late payments

1. Day 1 overdue: Send a polite reminder email with the invoice attached
2. Day 7 overdue: Follow up by phone as well as email
3. Day 14 overdue: Send a formal letter before action, stating you will apply statutory interest
4. Day 30+ overdue: Consider the Money Claim Online service (UK small claims) for amounts up to £10,000

Should you use invoicing software?

For occasional invoicing (1–3 clients per month), a clean PDF template downloaded and sent by email is perfectly sufficient. When invoicing more regularly, tools like FreeAgent, Wave, QuickBooks or even a well-formatted spreadsheet save significant time — especially at Self Assessment time when you need a clear record of all income.

Getting paid faster — practical tips

• Send the invoice the same day the work is delivered — never wait
• Make it easy to pay: include a payment link (Stripe, PayPal, GoCardless) alongside your bank details
• Follow up the day before the due date with a friendly reminder
• For large projects, invoice 50% upfront — this protects you and filters out unreliable clients