What is Email Invoice?

More and more entrepreneurs are sending their invoices by email. Sure, there are still many customers who will only accept an invoice if it is a paper invoice. But there is no doubt that electronic invoices, which include email invoices, are clearly on the rise and become more and more important. In addition, the electronic invoice is just as legally valid as the paper invoice. It doesn’t matter whether the invoice has a digital signature or not.

Definition – what is an email invoice?

What exactly do you have to imagine by an email invoice ? The definition states that this is a type of electronic invoice. The invoice recipient does not receive this invoice by post, but rather quickly and easily by email. As a rule, this invoice is attached to the mail as a PDF file or as an image file. However, it can also be integrated into the mail itself as a download link. An invoice by email must contain the same mandatory information for an invoice as you know it from the paper invoice.

E-mail invoices are legally valid

The paperless office is becoming more and more important and interesting for an entrepreneur. On the way there, however, that also means that you have to part with things like paper bills. There are still customers who value a paper invoice and only accept this. But that doesn’t mean that you have to stick to the paper invoice. But what about the legal situation for an invoice by email? Let’s deal with the following questions:

  • Is an email invoice valid?
  • Are e-mail invoices legally effective?
  • What about the GDPR?

The most important answer is that an email invoice is legally effective and valid. The only important thing for you is that it meets the same requirements as the paper invoice. This means that, for example, all mandatory information is available on the invoice. The subject of GDPR and data protection is also less bad than you might fear. The following points play an important role here:

  • Usually there are no personal data in an invoice from your company to another company.
  • When sending an invoice to an end customer, you must ensure that a possible risk of gaining knowledge or even misuse of the data contained in the invoice is minimized by technical measures.

Above all, this risk minimization is now done by numerous e-mail providers, because they provide transport encryption for the e-mails.

Benefits of invoicing by email

An invoice by email has advantages that you cannot dismiss. This includes:

  • Cost savings by eliminating material such as paper, postage, costs for printers and files for storage
  • Cost savings by minimizing working hours for preparing the invoices and the way to the post office
  • Cost savings through less space required, as digital invoices do not require storage space for storage
  • Time savings through easier and faster transmission of important information regarding the invoice

Email Invoice Checklist – 5 Important Requirements

So far, this may all sound pretty easy and problem-free to you. Nevertheless, there are a few things to consider when invoicing by email and you also have to meet certain requirements when it comes to data protection. In the following, we will go into more detail for you on everything that needs to be considered.

Mandatory information on the invoice by email

In 2011 the Tax Simplification Act was introduced. Since then, you have been able to send an invoice to your customers by email without a digital signature and without an EDI process. The same law applies to them as to the paper invoice. However, this also means that an invoice by email must contain the relevant mandatory information. This is the first basis for asking if you need to accept email bills. If you no longer know exactly which mandatory information is required, you can check it below:

  • Name and exact address of your company and the recipient of the invoice
  • your tax number or the sales tax identification number
  • the exact date of issue of the invoice
  • an invoice number that must be consecutive and is only issued once
  • the exact amount and type of delivery or the exact type and scope of the service provided
  • the time of delivery or the provision of services and the payment term
  • the entire remuneration with tax amount and valid tax rate
  • Agreements made in advance with regard to a reduction in pay

If you are a small business owner within the meaning of § 19 UStG, you do not have to show sales tax on the invoice by email. Instead, however, you must include a notice about the absence of sales tax. This can for example read as follows: “According to the small business regulation according to § 19 UStG no sales tax is charged.”

The recipient of the invoice by email must agree to this

You need consent for the invoice by email. This point may sound like a bigger problem to you now, but it really isn’t all that worrying. It is correct that the invoice recipient must agree that you want to send him the invoice electronically. However, no special form is required for a declaration of consent to the invoice by email. You can record this in an agreement and, for example, describe it in your terms and conditions and thus prevent a question, invoices by email are valid. You can create terms and conditions yourself or use a free terms and conditions template.

The invoice by email must be intact, legible and genuine

Next, let’s look at what an email invoice should look like. This is regulated in Section 14 (3) of the UStG. At this point it is stated that the authenticity of the origin of this invoice as well as the integrity of the content and legibility must be guaranteed. This may sound a bit complicated to you, too, but it can be solved quite easily. You can ensure this through a control procedure in your company. An audit trail simply has to be created between the invoice and the service.

Caution! Digital signature & signature for the invoice by email

There are only a few exceptions where a signature and signature are required for an invoice. This applies, for example, to tax consultants or lawyers. Otherwise there is no obligation for you to create a signature for the electronic invoice. This has been in effect since 2011. So you do not need to sign the electronic invoice and should instead omit the signature not only for the invoice by e-mail and also for the paper invoice. The reason for this is very simple. If your signature or digital signature is under an invoice, the burden of proof lies with you as the invoice issuer.

The invoice by email must be GoBD-compliant & archived

Now we come to a very important point, namely how you have to archive the invoices by e-mail in a legally secure manner. You always have to make sure that this is also GoBD-compliant. Regardless of whether you send invoices by email or receive invoices by email, they always have to be processed electronically. It is absolutely not permitted for such invoices to be printed out and then archived. They are to be kept in the same way as they were sent or received. A GoBD-compliant storage means:

  • the bill must legibly be
  • it must invariably be
  • the bill should not be manipulated to be

An invoice by email must be kept for 10 years

When archiving invoices by email, the subject of retention periods also plays an important role. The GDPR stipulates that you, as an entrepreneur, must ensure that an electronic invoice is kept for at least 10 years. During this period it must be possible for the electronic invoice to be found in the shortest possible time, for example during a tax audit, to be read and evaluated in the shortest possible time. To ensure this, you must always keep the original of your electronic invoices.

How does the tax office handle invoices by email?

The tax office expects you to keep all digital invoices, both sent and received, available for at least the duration of the retention period. The tax office does not recognize the archiving of an invoice in paper form if you have sent or received it in digital form. You are obliged to have them ready in digital form. You must also ensure that the content of such an invoice can never be changed. So you should send your invoices by email, so you also have to do this in a non-changeable file format. This is a legal requirement and applies to both the invoice recipient and the invoice issuer. It is important that you observe the following points:

  • File format
  • The most common formats
  • European directives

File format of the invoice via email

There are currently no specifications for the file format of an invoice sent by e-mail, from which it is clear which format it should be. In any case, you have to use a format that can not be changed. It is certain, however, that in the future there will be so-called hybrid formats that will play a dominant role in electronic invoicing. These hybrid formats are mixtures of a PDF file, an image file or structured data.

The most common formats for your invoice by email

The following formats are currently used very often for sending e-bills:

  • Structured data formats such as EDI or XML
  • Data formats that are not structured, such as jpg, PDF or tif formats
  • Hybrid data formats such as ZUGFeRD or PDF / A3

Which data format you as an entrepreneur in the private market economy use and send to consumers has not yet been specified and not regulated in a binding manner. It is simply important that legibility, authenticity and intactness can be ensured for your invoice by email for the entire retention period.

European guidelines for an invoice by email

At the European level it looks a little different. There are binding specifications here, which are set out in European Directive 204/55 / ​​EU and which are to be implemented. This guideline shows that only electronic invoice formats are valid and legally permitted that meet the following requirements:

  • The invoice formats must consist of structured invoice data
  • The calculation formats must be made of an image file (ZUGFeRD) and from structured data consist

In concrete terms, this means that a scanned paper invoice and another file, either PDF or an image without structured data, do not comply with the EU directive. In order to be sure about future regulations, you should use a format with structured data for sending an invoice by email.


If you want to send or receive an invoice by email, you can definitely increase the efficiency in your company. The costs not only decrease for you as the biller, but also for every bill recipient. You can digitize the entire invoice verification and create an automatic process. However, there are a few important facts to consider in connection with the electronic invoice. This applies to the retention period as well as to GoBD-compliant archiving and the mandatory details of an electronic invoice. When it comes to the format used for the invoice by email, you should use formats with structured data. Although this is not mandatory at the moment, it will play a decisive role in the future.

Email Invoice