# NLCIUS and SI UBL 2.0
How to use the basic invoice according to EN 16931-1. (opens new window) *Specification is in Dutch.
Difference between a correction invoice and a credit note
In the code block below there is a tab with CorrectionInvoice and a tab with CreditNote. When these XML's are compared, the data is different, but the outcome will be exactly the same. For example if the CreditNote structure is used, instead of an Invoice tag there will be a CreditNote tag, and instead of InvoiceTypeCode, CreditNoteTypeCode wil be used.
In UBL there are schemas for two types of messages: Invoice and Credit Note. In the Credit Note the line totals and the invoice total are positive when the customer receives a refund and negative if the buyer has to pay. In that case, instead of the Credit Note the Invoice scheme can also be used, but with negative (line) totals. A negative line total is created by entering a negative quantity, multiplied by a positive price. Prices are always positive.
In the NLCIUS working group, the starting point is to use the regular Invoice message (combination of positive and negative amounts) and not the separate Credit Note message. In the Dutch market and existing standards (SI-UBL, SETU, SALES, etc.) it is customary to work this way. This avoids common problems when it comes to the interpretation of the sign (positive/negative) of quantities and amounts. This means that invoicing, crediting, returning and/or correcting is done via one and the same invoice format.
The Invoice type code (BT-3) only gives an indication of the type of invoice and has no meaning in the interpretation of quantities and amounts. To avoid confusion we advise against using code 381 (Credit Note) and all variants. Invoices from abroad can use this code, so receiving systems must be prepared for Credit Notes to be able to receive them. Code 381 may only be used in conjunction with the Credit Note scheme.