What must an invoice contain? The 10 legal requirements

The 10 requirements for a full invoice

A payment deadline and bank details are not legal requirements, but they belong on the invoice in practice — without them, the customer doesn't know when or where to pay.

• Invoice date (the date of issue)
• A sequential invoice number
• Your CVR number (VAT registration number)
• Your name and address
• The buyer's name and address
• The quantity and nature of the goods or services supplied
• The delivery date, if it differs from the invoice date
• The unit price excluding VAT, and any discounts
• The VAT base and the applicable VAT rate (typically 25%)
• The VAT amount itself in kroner

Simplified invoices for small sales

For sales under 3,000 kr. a simplified invoice — such as a till receipt — is enough. It must still show the date and number, your name and CVR number, what was supplied, and the VAT amount. If a business customer asks for a full invoice, though, you must issue one.

Invoices without VAT

If you sell VAT-exempt services, or to businesses in other EU countries under the reverse-charge rules, the invoice must explain why no VAT is added — for example with the wording "reverse charge" and the buyer's VAT number. Without the explanation, the invoice isn't valid and your customer can run into trouble with their own deduction.

Mistakes are fixed with a credit note

If you've sent a wrong invoice, you must not simply delete or overwrite it — the number sequence has to stay unbroken. Instead, issue a credit note that cancels the wrong invoice, and create a new one with the correct content. The credit note must reference the original invoice.

Selling to the public sector: e-invoicing

Public-sector customers can't accept PDF or paper invoices. They must receive an electronic invoice sent via NemHandel to the institution's EAN number — an accounting system with e-invoicing handles that for you.

Storage and bookkeeping

Invoices are accounting records and must be kept for at least 5 years after the end of the financial year — both the ones you send and the ones you receive. Under the Danish Bookkeeping Act this must happen digitally in a bookkeeping system, so drop the binder and let the system store them automatically.

Invoicing with the bookkeeping included

In Numina's accounting software your invoices meet the requirements automatically: sequential numbering, correct VAT and e-invoices for public-sector customers. And because the bookkeeper is part of the price, every invoice is also booked, reconciled against the payment and included in your VAT return — without you lifting a finger.

The terms behind it, briefly explained

Finally a quick glossary of the terms from this article — brief and concrete, the way we explain them to our customers.

What is a faktura (invoice)?

A faktura is an invoice with legally required contents: invoice number, date, the seller's CVR number, description, amount and VAT.

Sequential numbering is required, and the invoice doubles as your receipt in the books. Invoices to the public sector must be sent electronically via an EAN number.

What is a kreditnota (credit note)?

A kreditnota is a 'reverse invoice' that cancels or reduces an earlier invoice — e.g. for errors, returns or discounts.

Never edit a sent invoice: issue a credit note and, if needed, a new invoice. That keeps both the VAT and the audit trail straight.

What is a proformafaktura (pro forma invoice)?

A proformafaktura is an invoice for information only — no payment obligation. It is used for customs papers on exports, product samples, or as the basis for prepayment.

A pro forma invoice is not an accounting document and triggers neither VAT nor a receivable. Once the sale goes through, a real invoice with a sequential number must always be issued — that is the one that gets booked.

What is an e-faktura (e-invoice)?

An e-faktura is an invoice in a structured digital format (OIOUBL or Peppol, say) sent directly between accounting systems — not a PDF by email.

Public-sector customers must receive e-invoices, so selling to the state or a municipality requires invoicing via NemHandel to the customer's EAN number. Registered digital bookkeeping systems must support e-invoices, and the format is gaining ground between private businesses too.

What is an EAN number?

An EAN number (GLN) is the electronic address Danish public institutions receive e-invoices on. Invoices to the state, regions and municipalities must be sent electronically to the customer's EAN number.

Selling to the public sector requires invoicing software that supports e-invoicing (OIOUBL/Nemhandel) — Numina's invoicing does.

What is betalingsbetingelser (payment terms)?

Betalingsbetingelser are the terms deciding when and how an invoice must be paid — net 8 days, or end of month plus 14 days, for example.

Between businesses the payment term may as a rule be at most 30 days, unless a longer term is explicitly agreed. On late payment you can add default interest, reminder fees and a fixed compensation amount. Short terms are the easiest route to better liquidity.

What is a debitor (debtor)?

A debitor is a customer who owes the business money — typically an invoice that hasn't been paid yet.

The sum of debtors (receivables) sits as an asset on the balance sheet. Keep the list short: money sitting with customers is poor liquidity.

What is a kreditor (creditor)?

A kreditor is a supplier or other party the business owes money — e.g. an unpaid supplier invoice.

Creditors sit as debt on the balance sheet. Being on top of them means paying on time — but not earlier than necessary.

What is a rykker (payment reminder)?

A rykker is a written reminder about an overdue payment. You may charge a DKK 100 fee per reminder, at most three times with at least 10 days between them.

After three reminders the claim can go to debt collection — with notice. Automatic reminders solve most cases before it gets that far.

What is tab på debitorer (bad debts)?

Tab på debitorer are invoices customers never pay. Confirmed losses are tax deductible, and the VAT can usually be reclaimed.

The loss must be confirmed — through bankruptcy, failed collection or the enforcement court; for claims under DKK 3,000, your own failed reminders suffice. That is why systematic reminders and reacting quickly to non-payment pay off.