Invoice and quotation: how to get paid on time, every time

What your invoice must legally include, how to write a binding quotation, and why a signed contract cuts payment delays by weeks.

Invoice and quotation: get paid on time

An invoice is not just an afterthought — it is a legal instrument that creates the right to be paid. If something is missing or wrong, clients can delay payment legitimately.

What an invoice must legally contain (EU)

Under EU VAT Directive (2006/112/EC) and national tax laws, a valid invoice must include:

1. A unique sequential invoice number.
2. Issue date and the date of supply (when goods or services were delivered).
3. Supplier details — name, address, VAT number (if registered).
4. Customer details — name and address.
5. Description of goods or services — what was delivered, how much, at what unit price.
6. VAT breakdown — taxable amount, VAT rate, VAT amount (if applicable).
7. Total amount due and currency.
8. Payment due date — the EU Late Payment Directive (2011/7/EU) sets a default of 30 days for B2B transactions.

Missing any of these elements can give a client grounds to dispute the invoice — and delay payment.

Quotation: binding or non-binding?

A quotation (offer) can be binding or informational, depending on how it is worded. A binding offer commits the sender until the stated validity period expires. If the client accepts, a contract is formed — no additional signature required.

Practical tip: Always state a validity period (“This quotation is valid for 14 days”) and the conditions of acceptance. Without this, a client can come back six months later and claim the price still applies.

Why people get paid late — and how to fix it

The most common reasons for late payment:

• Vague description on the invoice.
• Missing bank details (IBAN, payment reference).
• The invoice gets buried in an email thread.

The fix: sign a contract before starting work that spells out the price, payment schedule, and a late-payment penalty. Then the invoice is simply a reminder — not a surprise.

How zipzipdoc helps

zipzipdoc lets you:

• Generate a quotation with a validity date and acceptance conditions.
• Embed payment terms directly in the contract (due date, penalties, IBAN).
• Have the client sign before you start, creating an undisputable record of the agreed price.

Once the work is done, your invoice is backed by a signed agreement — and clients pay faster.

Start free — 14 days, no card.