Invoice | What is an invoice?

Commercial document that contains the information of a buying and selling intervention. This document shows the delivery and payment of a product or service.

Self-employed and entrepreneurs are obliged to comply with invoicing regulations or, in other words, to issue invoices. So, if you are determined to start up your own business or your own company, it is essential that you have a thorough knowledge of these regulations. It is vitally important to know what an invoice is and what types of invoices exist, since only in this way will you be able to comply with the invoicing obligation.

What is an invoice?

An invoice is a commercial document with legal and fiscal validity that serves to accredit a sale or purchase of a good or service. Thus, this document contains all the information related to the transaction, from the identification of the issuer and receiver of the invoice to the description of the goods and services that are the object of the sale or purchase.

Who is obliged to issue invoices?

In accordance with Article 1 of the Regulation governing Invoicing Obligations, entrepreneurs or professionals are obliged to issue and deliver invoices in the course of their business or professional activity. Thus, they will be obliged to issue invoices in any of the following cases:

  • When the client is a private individual and he/she requests the invoice.
  • When the client is a businessman or self-employed.
  • When the export of goods that are exempt from VAT is carried out.
  • When the client is a body or entity of the Public Administration or a legal person that does not have the consideration of company or self-employed.
  • When a distance sale is carried out.
  • When a sale subject to special taxes is carried out.

What types of invoice can I issue?

There are different types of invoices, each of them indicated for one or another circumstance. Thus, depending on the commercial operation to be carried out, one type or another should be used, so it is essential to know when to use each model.

Regular invoice 

This model of invoice is the most commonly used, as it documents a commercial transaction involving the purchase and sale of goods or the provision of a service. Thus, an ordinary invoice is the physical document that proves a commercial transaction and contains detailed information about it.

The information that this invoice form must contain is as follows:

  • Invoice number.
  • Date of issue of the invoice.
  • Name and surname or company name of the issuer.
  • VAT number of the issuer.
  • Address of the issuer and of the recipient.
  • Personal income tax withholding.
  • Tax rate.
  • Total price of the operation. (Including VAT)
  • Date of the purchase or sale transaction or of the provision of the service.

Rectification invoice

As a consequence of the ordinary invoice, a corrective invoice may be used when a previous invoice (usually ordinary) has to be corrected when it does not meet the requirements of the invoicing regulations. They are also used when products are returned or when there are discounts after the purchase-sale.

This type of invoice may only be issued when the reasons justifying its issuance exist, provided that no more than 4 years have elapsed since the invoice to be rectified was issued.

This type of invoice must contain the details of the ordinary invoice, as well as the following:

  • Identification of the rectifying invoice, such as the invoice number or its date of issue.
  • Correction and the reasons for it.
  • Condition of the corrective invoice.
  • Tax rate and amount charged, taking into account the rectification that has been carried out.

Summary invoice

The recapitulative invoices include in a single invoice more than one commercial operation with the same recipient that have been carried out on different dates, but within the same month. However, when the recipient of the invoice is an entrepreneur acting as such, the recapitulative invoice must be issued before the 16th day of the month following the month in which the transaction was carried out.

Proforma invoice template

This type of invoice documents a commercial offer. It shows the determined price at which the entrepreneur will sell a series of products or provide a series of services. The purpose of the proforma invoice is to provide as much information as possible about the purchase to be made, so it has no accounting value and does not serve as a supporting document.

Simplified versus complete invoice template

Depending on whether the invoices have more or less information, the invoices may be complete or simplified.

  • Simplified invoice: this type of invoice will be issued when the amount of the transaction does not exceed 400 euros including VAT and it is requested by the issuer. This type of invoice only contains the issuer’s data, not being necessary the fiscal data of the receiver of the invoice.
  • Complete invoice: the complete invoice is the same as the ordinary invoice, so it will contain the data we have already referred to.

Electronic invoice template

These invoices are equivalent to a paper invoice, so they will be treated in the same way, although it is true that the electronic invoice is transmitted telematically.

For it to be valid, it will have to comply with the requirements that any other invoice must comply with, containing the mandatory data already mentioned.

We have created this table as a summary:


Regular invoice It contains all the information required according to the regulations. It shows the delivery details of the products or services, along with the applicable price and taxes.
Simplified invoice It contains less information than an ordinary invoice. The buyer is not included. Essential information: who issues the invoice, goods or services supplied and total compensation.
Rectification invoice or credit note It contains the same information as the invoice to be returned. It is used for goods returns or to correct errors in a regular invoice.
Summary invoice Grouping of dispatch notes or invoices. In the case of grouping of invoices, previous invoices must be voided for it to have fiscal validity.
Proforma invoice Similar to an estimate, used only as a draft. Provisional invoice for a future commercial activity.
Copy of the invoice Duplicate of the original invoice for the customer. It contains the same information as the original invoice, and it is issued in the event that the original is lost.
Electronic invoice Invoice in electronic format. It is issued and received in electronic format and it has the same legal effects as paper invoices.

Mandatory contents of an invoice in accordance with the invoicing regulations

All invoices must include certain data or contents on the existence of which the legal and fiscal validity of the invoice will depend. These obligatory data are the following:

  • Invoice number and series.
  • Date of issue of the invoice.
  • Date of the commercial transaction, except when this date coincides with the date of issue.
    NIF, name and surname and company name of the entrepreneur or self-employed person issuing the invoice.
  • Identification of the goods or services that are the object of the sale or purchase.
  • Tax rate and tax liability.
  • When the invoice is exempt from VAT, this must be specified in the invoice.
  • Advance payment or discount if applicable.
  • Total consideration, the price paid by the invoice recipient for the goods and services.

In addition, certain circumstances must be stated in the invoice, such as the cases in which the transaction is exempt in accordance with the regulations, or when the Special Regime for Travel Agencies or the Special Regime for Used Goods are applicable, among other circumstances.

With an online invoicing program, the possibilities of increasing your company’s performance increase proportionally.

You will have all your invoices centralized, with access from anywhere, without installing programs on your PC. STEL Order is considered by our customers as the best online invoicing program. It allows you to have all your business documents on the same platform, along with your customers and products, plus the mobility offered by our APP on both Android and iOS.

Try it FREE for 15 days without obligation.

Alberto Abad

CFO. Ingeniero de telecomunicaciones al que le encanta la contabilidad y fiscalidad. Lidera el desarrollo del programa de facturación líder que hace la vida más fácil a miles de autónomos y pymes.

Linkedin profile

Last articles

How to create a client information sheet

Every company owes its customers, so being in possession of as much customer information as possible by companies is a mandatory task if it wants to take advantage of one of the greatest competitive advantages a company can have is its own customer base.

How to attract more customers in 2020?

The best tips to increase your sales in digital media by Bernardo Salazar, guest author who gives us digital marketing tips to apply in your company. Generate active communication with your customers and attract more sales this 2020.

Distribute in Spain

We analyze the main characteristics of the distribution sector in the world, Europe and, mainly, for distribution in Spain. We tell you which items European and Spanish consumers have invested the most in. With the TOP ranking you know which companies are protagonists.

What is market research and how to conduct it?

In this article we explain how to do a step-by-step market research and how it will help you to grow your business.

This site is registered on as a development site.