Sending your first invoice can feel oddly daunting. You’ve done the work — now you need a document that holds up legally, gets processed by accounts payable without issues, and actually results in money hitting your account. Here’s what that document needs to contain.
Required information
Most countries have legal minimum requirements for invoices. Miss any of these and your client’s accounting team may send it back before it even enters their payment queue.
Every invoice must include:
- Your full name and address — or your registered business name and address if you operate under one
- Your client’s full name and address — the exact legal entity you’re billing, not just a contact name
- A unique invoice number — sequential, never repeated (more on this below)
- Invoice date — the date you issued the document
- Due date — when you expect payment
- Description of the work — specific enough that someone who wasn’t involved understands what was delivered and when
- Line items and amounts — individual charges listed clearly, with any applicable taxes shown as a separate line
- Your tax or VAT number — required in most countries once you’re registered; see below
- Your payment details — IBAN and BIC for EU bank transfers, or however you receive payment
For Germany specifically, invoices above €250 must also include the date the service was performed (which can differ from the invoice date), and the net amount before tax must be stated separately from the tax amount.
Suggested layout
There is no single mandatory layout, but a structure that works reliably:
- Your details (top left) — name, address, email, tax/VAT number
- Invoice metadata (top right) — the word “Invoice”, invoice number, issue date, due date
- Client details — their legal name and address
- Line items table — description, quantity, unit price, amount per line
- Totals block — subtotal, VAT amount (if applicable), grand total
- Payment details — IBAN, BIC, or however you receive payment
Invoice numbering
Invoice numbers must be unique and sequential — no gaps, no duplicates. The format is your choice:
| Format | Example | Good for |
|---|---|---|
| Simple sequence | 001, 002, 003 | Just starting out |
| Year-prefixed | 2026-001, 2026-002 | Resets each year, easy to audit |
| Client-prefixed | ACME-001, ACME-002 | High volume, many clients |
Never delete or reuse an invoice number. If you made an error on an invoice, issue a credit note that cancels it, then issue a corrected invoice with a new number. Tax authorities in most countries expect a clean, unbroken sequence — gaps raise questions.
Start at 001 or 1001, not a random number. Numbering from 1 on your very first invoice is fine; numbering from 5000 to look more established than you are is not worth the audit risk.
VAT — do you need to charge it?
Only if you are registered for VAT. Below the registration threshold in your country you trade without VAT entirely — no VAT line on your invoice, no VAT number required.
Thresholds vary: Germany’s is €25,000 (annual turnover), the UK’s is £90,000. If you’re below the threshold, your invoice total is the net amount and nothing more.
If you are VAT-registered, you must:
- Show the net amount, the VAT rate, the VAT amount, and the gross total as separate lines
- Include your VAT number on the invoice
- Never show VAT without a valid VAT number — that is illegal in most jurisdictions
For a full breakdown of VAT registration and rates, see our VAT guide.
Which tax number goes on the invoice?
This trips up almost every first-time freelancer.
Most countries give you a personal tax ID (a lifetime number tied to you as an individual) and a separate business or VAT number (tied to your trading activity). Only the business or VAT number belongs on an invoice. Your personal tax ID is for filing your own tax return — clients have no use for it.
In Germany: use your Steuernummer if you’re a Kleinunternehmer, or your USt-IdNr. if you’re VAT-registered. Never use your personal Identifikationsnummer (IdNr.) on invoices. For the full picture, see our guide on German business ID numbers.
When to send the invoice
Send it as soon as the work is complete. Not the next day, not at the end of the month — immediately. Clients process invoices in batches; the earlier yours arrives, the earlier it gets into the payment queue for that cycle. Waiting a week to invoice often means waiting an entire extra payment cycle to get paid.
For ongoing retainers, pick one day each month and send on that day without exception.
In Billino
Add your tax or VAT number to your sender profile and Billino puts it on every invoice automatically. If you’re a Kleinunternehmer, enable that option and Billino adds the legally required §19 UStG note without any manual editing. Every invoice is a correctly formatted PDF, ready to send.
