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Check your e-invoice for free.

Upload an XRechnung file or a ZUGFeRD PDF. The checking program of Germany’s coordination office for IT standards (KoSIT validator 1.6.3) tests it on our server in Germany. You then see which rules the file breaks, with the common ones explained in plain English and often how to fix them.

For invoices between businesses in Germany, e-invoices are becoming mandatory (section 27(38) of the German VAT Act, UStG). From 1 January 2027 this applies to businesses with more than €800,000 turnover in the previous year. From 1 January 2028 it covers all of them, with exceptions such as small businesses under the German small business scheme (“Kleinunternehmer”) and invoices up to €250 gross.

  • XRechnung and ZUGFeRD
  • free
  • we don’t store the file

Only upload invoices you may share, ideally a sample invoice. Invoices with health details, for example from labs or medical practices, do not belong here. Section 8 of our privacy policy explains what happens to the file.

Which invoices belong here

Only upload invoices you may share, ideally a sample invoice. Invoices with health details, for example from labs or medical practices, do not belong here. Section 8 of our privacy policy explains what happens to the file.

Result for an XRechnung with no buyer reference.

This is how the check shows a test invoice without a buyer reference. Every finding sits in one of six groups, and each group comes with a general note and its source.

File structure

Germany’s Federal Ministry of Finance (BMF) calls it a format error when a file does not meet the technical requirements of its format. For VAT purposes such a file counts as an “other invoice in another electronic format” (“sonstige Rechnung”). The kind of format error makes no difference (BMF letter of 15 October 2025, para. 6a). Source, retrieved 23 October 2026

EN 16931 rules

If the check reports an error against an EN 16931 rule, the file technically no longer counts as an invoice under that standard. Germany’s Federal Ministry of Finance (BMF) says this technical view does not decide VAT questions. Without a format error, the file is in principle still an e-invoice under section 14 of the German VAT Act, UStG (BMF, 15 October 2026, paras. 22–23). For the BMF, an error can only be a content error if it concerns a detail that VAT law requires on invoices (BMF, 15 October 2026, para. 22, and 15 October 2025, para. 35a). Whether that applies to your invoice is for your tax advisor to judge. Source, retrieved 23 October 2026 Further source, retrieved 23 October 2026

XRechnung rules

These rules belong to the XRechnung rule set and go further than the EN 16931 standard. For VAT purposes, any format that follows this standard is permitted (VAT Application Decree, UStAE, section 14.1(11)). Which one applies is for you to agree with your customer or supplier (section 14.1(12)). For Germany’s Federal Ministry of Finance (BMF), a rule error can only be a content error if it concerns a required invoice detail under VAT law (BMF, 15 October 2026, para. 22). Whether that applies to your invoice is for your tax advisor to judge. For invoices to public authorities and other public contracting bodies, further rules apply alongside VAT law, such as the federal E-Invoicing Ordinance (E-Rechnungsverordnung; paras. 24 and 25). Source, retrieved 23 October 2026 Further source, retrieved 23 October 2026

Peppol BIS Billing 3.0 rules

These rules belong to the Peppol BIS Billing 3.0 rule set and go further than the EN 16931 standard. For VAT purposes, any format that follows this standard is permitted, even one that does not come from Germany (VAT Application Decree, UStAE, sections 14.1(11) and 14.1(12)). Which one applies is for you to agree with your customer or supplier (section 14.1(12)). For Germany’s Federal Ministry of Finance (BMF), a rule error can only be a content error if it concerns a required invoice detail under VAT law (BMF, 15 October 2026, para. 22). Whether that applies to your invoice is for your tax advisor to judge. Source, retrieved 23 October 2026 Further source, retrieved 23 October 2026

ZUGFeRD profile

Germany’s Federal Ministry of Finance counts ZUGFeRD from version 2.0.1 among the permitted e-invoice formats, except the MINIMUM and BASIC WL profiles (UStAE section 14.1(14)). Source, retrieved 23 October 2026

Outside this check

This check does not cover this version or format. It covers XRechnung 3.0 and invoices that follow the EN 16931 standard without additions. For Peppol BIS Billing 3.0, it checks files that start with Invoice or CreditNote.

The file does not meet all the rules we checked.

1 error, 1 note XRechnung 3.0

XRechnung rules

These rules belong to the XRechnung rule set and go further than the EN 16931 standard.

What this means

These rules belong to the XRechnung rule set and go further than the EN 16931 standard. For VAT purposes, any format that follows this standard is permitted (VAT Application Decree, UStAE, section 14.1(11)). Which one applies is for you to agree with your customer or supplier (section 14.1(12)). For Germany’s Federal Ministry of Finance (BMF), a rule error can only be a content error if it concerns a required invoice detail under VAT law (BMF, 15 October 2026, para. 22). Whether that applies to your invoice is for your tax advisor to judge. For invoices to public authorities and other public contracting bodies, further rules apply alongside VAT law, such as the federal E-Invoicing Ordinance (E-Rechnungsverordnung; paras. 24 and 25). Source, retrieved 23 October 2026 Further source, retrieved 23 October 2026

Error: The buyer reference is missing, rule BR-DE-15
How to fix it
Enter the reference your customer gave you. For German federal authorities this is the Leitweg-ID, which the authority states with its order. If you have no reference, ask your customer for one.
VAT, in general
Germany’s Federal Ministry of Finance cites a missing buyer reference (BT-10) as an example of a rule error that does not matter for VAT. Whether your customer needs the entry anyway depends on your agreement with them. Invoices to German federal authorities need the Leitweg-ID in this field (section 5 of the federal E-Invoicing Ordinance, E-Rechnungsverordnung; BMF, 15 October 2026, paras. 24 and 25). Source, retrieved 23 October 2026
In Lexware Office

Lexware Office keeps the Leitweg-ID on the customer record, under contacts (“Kontakte”), edit contact (“Kontakt bearbeiten”), section “E-Rechnung”, field “Leitweg ID”. First check that Lexware Office created the invoice as an XRechnung. Once the ID is in place, open the invoice for editing, save it and download the XML file again.

Vendor’s help page, retrieved 23 October 2026
In sevdesk

sevdesk calls the buyer reference “Kundenreferenz / Leitweg-ID”. The field sits in the lower part of the invoice form under “Weitere Optionen”. If the Leitweg-ID belongs on every invoice to this customer, switch on “E-Rechnung Standard” in the contact and enter it there. According to the help page, sevdesk writes 0 as the customer reference when you leave the field empty.

Vendor’s help page, retrieved 23 October 2026
In DATEV

In DATEV Auftragswesen next, the buyer reference belongs in the customer record, in the customer reference field (“Kundenreferenz”). A public authority’s Leitweg-ID goes there too. The program uses the field once “E-Rechnung” is selected as the invoice format under general invoice data (“Allgemeine Rechnungsdaten”) for that customer. The field also decides how the invoice is sent. Without an entry, it goes out by email as ZUGFeRD. With a TRAFFIQX ID (prefixed “TX:”) or a Leitweg-ID, it goes through a portal, provided the recipient is registered there. For an invoice that is still a draft, select the customer in it again so the draft picks up the changed details. DATEV E-Rechnungsschreibung calls the same field “Leitweg-ID/ Kundenreferenz” (document no. 1028945).

Vendor’s help page, retrieved 23 October 2026
What the rule requires

XRechnung requires a buyer reference (BT-10) on every invoice. The rule reports an error when that entry is missing or holds nothing but spaces. EN 16931 lists the buyer reference as optional; this XRechnung rule makes it mandatory.

Common cause
This happens when the customer never supplied a reference, or when it is missing from the customer record in the invoicing software.
Details concerned
BT-10 EN 16931 gives every detail of an e-invoice a number, such as BT-10 for the buyer reference. BG numbers stand for groups of details.
Where in the file

The path leads from the outside in to the entry in the XML file that the rule reports.

  • /Invoice[1]
Ask ChatGPT (opens in a new tab)

The button opens chatgpt.com in a new tab with a question about this rule. The question holds only the code and, where we have one, our explanation, nothing from your invoice. OpenAI receives it when you click. Technical explanation, not tax advice

Note: No delivery date or service period, rule BR-DE-TMP-32
How to fix it
Add the delivery date or an invoicing period for the whole invoice. If you prefer periods per line, give every line one, including minor items such as shipping.
VAT, in general
The German VAT Act lists the date of the supply of goods or services as a required invoice detail (section 14(4) sentence 1 no. 6 UStG). A mapping table by KoSIT, Germany’s coordination office for IT standards, and FeRD, the German e-invoicing forum, puts it in BT-72, BG-14 and BG-26. Germany’s Federal Ministry of Finance (BMF) recommends basing e-invoices on this table (BMF, 15 October 2026, paras. 8 and 9). According to the BMF, every required detail belongs in the machine-readable part of an e-invoice (BMF, 15 October 2025, para. 35). Source, retrieved 23 October 2026
In Lexware Office

In the Lexware Office invoice editor the date sits in the customer details (“Kundenangaben”), in the delivery date field (“Lieferdatum”). Switch that field to service period (“Leistungszeitraum”) and enter a start and end date, or to service date (“Leistungsdatum”) for a single day. Lexware asks for the service period on e-invoices.

Vendor’s help page, retrieved 23 October 2026
In sevdesk

The sevdesk invoice form has a “Lieferdatum” (delivery date) field. To have it filled in on every new invoice, turn on “Lieferdatum automatisch setzen” under “Einstellungen”, “System”, “Aufträge & Rechnungen”. The help page leaves open which date sevdesk enters, so look at it before you send the invoice.

Vendor’s help page, retrieved 23 October 2026
In DATEV

In DATEV Auftragswesen next, the date goes into the date of supply field (“Liefer- & Leistungsdatum”) while you edit the invoice. Clicking the icon that belongs to it switches the field to period of supply (“Liefer- & Leistungszeitraum”), where you enter a period instead. According to DATEV’s help, Auftragswesen next will not save the invoice while this field is empty.

Vendor’s help page, retrieved 23 October 2026
What the rule requires

XRechnung recommends that the invoice states when goods were delivered or services performed. One of these is enough: the delivery date (BT-72), an invoicing period for the whole invoice (BG-14) or a period on each line (BG-26). The XRechnung rule set classifies this rule as a notice.

Common cause
The invoice lacks both a delivery date and an invoicing period. The notice also appears when only some lines carry a period, for example when a shipping line has none.
Details concerned
BT-72, BG-14, BG-26 EN 16931 gives every detail of an e-invoice a number, such as BT-10 for the buyer reference. BG numbers stand for groups of details.
Where in the file

The path leads from the outside in to the entry in the XML file that the rule reports.

  • /Invoice[1]
Ask ChatGPT (opens in a new tab)

The button opens chatgpt.com in a new tab with a question about this rule. The question holds only the code and, where we have one, our explanation, nothing from your invoice. OpenAI receives it when you click. Technical explanation, not tax advice

Product names mentioned here, including OpenAI’s ChatGPT, are trademarks of their respective owners. We are not a partner of these companies.

Test invoice 01.01a from KoSIT’s test suite (Apache-2.0 licence), with the buyer reference removed by us. The sample is built into the page and sends nothing to the checking program.

Result for an XRechnung with no buyer reference

Before you upload.

Which files does the check cover?

The check covers XRechnung files, Peppol invoices and other invoices that follow the EN 16931 standard. You upload an XML file up to about 2.1 MB or a PDF up to about 5.2 MB with an XML file inside, as in ZUGFeRD. The XML file is the part of an e-invoice that invoicing software reads. The check recognises ZUGFeRD profiles other than EN 16931, ZUGFeRD 1.0 and older XRechnung versions. For these, the result says that it does not test their rules.

What happens to my file?

Your browser sends the file to our server in Germany only when you click “Check invoice”. KoSIT’s checking program tests it there, usually in under a second. The file stays in working memory only, and we don’t store it. Your browser does not even send the file name. Each day we count which rules were broken how often, without names, amounts or invoice numbers. Section 8 of our privacy policy has the details.

What does the check not cover?

Whether the invoice is right for tax purposes, such as the VAT rate and the required details, is for your tax advisor to judge. For a PDF the check only tests the embedded XML file. It does not look at the visible part or at how the PDF itself is built. It does not yet test the specific rules of the ZUGFeRD profiles BASIC and EXTENDED.

How often can I check?

You can check up to 20 files an hour and 50 a day, free and without signing up. All visitors together share a limit of 2,000 checks a day. If the checking program cannot be reached, the attempt does not count.

We answer questions about the check in the chat.

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Please do not send us invoice files by chat or email.