Invoice

Which tasks the invoice has

The invoice is the document that settles a delivery. It serves three purposes at once: it shows the customer the amount, it serves the retailer as a booking record and it is evidence for VAT. A fourth, less visible task comes on top: it documents what was sold at which price and is therefore the basis in a dispute about scope or condition.

Which details must be included

• Parties: full name and address of retailer and customer.
• Identifiers: the retailer's tax number or VAT identification number, plus the customer's number for services to businesses.
• Invoice number: a consecutive number issued once. It must not occur twice.
• Date: the issue date and, where it differs, the service date.
• Goods and scope: quantity and customary description of the goods delivered.
• Consideration: the net amount, the tax rate and the resulting tax amount, plus the gross amount.

When it is issued

In principle the invoice has to be issued within a short period after the service, and that period binds both sides. In practice an online shop sends it with the order confirmation or with dispatch. Both routes are permitted but have different consequences: an invoice issued before delivery documents a claim, an invoice with dispatch documents a delivery.

The order matters with part deliveries. If only part is shipped, a separate invoice is required for it. Anyone billing the whole order in advance and then delivering in parts runs into trouble on a cancellation, because the mapping is missing.

What applies to small amounts

For invoices up to a low amount there are reliefs. The customer's name and address are then not required in full, and the details on the tax rate can be simplified. That relief is of little relevance in retail, because it applies only to small single amounts and not to the total of an order.

Which mistakes lead to later claims

Four mistakes appear regularly. First the duplicate invoice number, usually through two parallel systems. Second a wrong tax rate, because the item was set up incorrectly. Third an incomplete name, because the customer abbreviated while filling in the form and nobody checked. Fourth the missing service date for services not performed on the invoice date.

One point often overlooked comes on top: the invoice has to be kept unchanged. When an invoice is corrected later, that happens with a separate document and not by overwriting. Anyone deleting the original version can no longer trace the transaction, and an audit finds a gap.

Frequent questions

• Is a PDF file enough? Yes, an electronic invoice is permitted.
• Do I have to issue one for every order? Yes, it is mandatory for every delivery.
• How long to keep it? The retention period is several years and set by tax law.