Retaining e-invoices: data set, period and archive

The original of an e-invoice is its structured data set. It is kept unchanged in the format received, for eight years under section 14b of the German VAT Act (UStG). A printout or a PDF image does not replace it. How your archive has to be built in detail so that it meets the tax authorities’ principles is for your tax adviser to clarify.

1. Unalterable storageWrite protection, logging, backup, access rights
2. Original data setXML with embedded attachments in the format received, eight years
3. IndexInvoice number, date received, project number, approval
4. Procedural documentationWho files, checks, backs up and deletes, and how

Text version of the graphic

• Layer 1 from the bottom: Unalterable storage, Write protection, logging, backup, access rights
• Layer 2 from the bottom: Original data set, XML with embedded attachments in the format received, eight years
• Layer 3 from the bottom: Index, Invoice number, date received, project number, approval
• Layer 4 from the bottom: Procedural documentation, Who files, checks, backs up and deletes, and how

What is archived

For an XRechnung that is the XML file, for ZUGFeRD the embedded XML. For VAT purposes the Federal Ministry of Finance (BMF) requires that at least the structured part is kept so that it exists intact in its original form (BMF 2025, margin no. 60). The GoBD, the principles for the proper keeping of books and records in electronic form, say the same in the version of 14 July 2025: the structured part is sufficient (margin nos. 119 and 131). The PDF image of a ZUGFeRD invoice has to be kept in addition only if it contains further or differing details of tax relevance, for example posting notes or qualified electronic signatures (margin no. 131).

Embedded attachments such as the bill of quantities or timesheets are inside the file, so archiving the file unchanged keeps them. Whether individual attachments matter for tax is a question for the tax adviser.

If the email that brings the invoice serves solely as a means of transport, like an envelope, the Federal Chamber of Tax Advisers says it need not be kept in addition. That does not apply if the email itself contains details that must be retained. You may keep it voluntarily as evidence of sender and time. It is best to keep the validation report too; the BMF names it as proof (BMF 2025, margin no. 35a).

Invoices you issue must also be kept (section 14b(1) UStG). If you use invoicing software, the GoBD do not require a pictorial copy from the moment of creation, provided you can produce a duplicate identical in content at any time (margin no. 76 as amended on 14 July 2025). How to prepare for issuing is covered in the article Issuing e-invoices: preparing a design practice.

For how long

Under section 14b(1) UStG, invoices must be kept for eight years. The period starts at the end of the calendar year in which the invoice was issued. It also applies to older invoices whose retention period was still running at the end of 2024 (section 27(40) UStG). Anyone who intentionally or recklessly fails to keep an invoice for at least eight years commits an administrative offence (section 26a(2) no. 2 UStG). The Fiscal Code (Abgabenordnung, AO) gives other periods for other documents:

Document	Period	Source
Invoices, received and issued	8 years	§ 14b(1) UStG
Accounting vouchers	8 years	§ 147(3) sentence 1 and (1) no. 4 AO
Commercial or business letters, other documents	6 years	§ 147(3) sentence 1 AO
Books, inventories, annual accounts	10 years	§ 147(3) sentence 1 and (1) no. 1 AO

An example with an invented date: for an invoice dated 12 March 2027 the period starts at the end of 2027 and ends after eight years at the end of 2035.

1. 12.3.2027 Invoice issued example with an invented date
2. 31.12.2027 The period starts at the end of the calendar year of issue
3. 31.12.2035 Standard 8-year period ends under section 14b(1) UStG
4. from 1.1.2036 Earliest possible deletion only if no longer period applies (section 147(3) sentence 5 AO)

Text version of the graphic

• 12.3.2027: Invoice issued. example with an invented date
• 31.12.2027: The period starts. at the end of the calendar year of issue
• 31.12.2035: Standard 8-year period ends. under section 14b(1) UStG
• from 1.1.2036: Earliest possible deletion. only if no longer period applies (section 147(3) sentence 5 AO)

The period can run longer. Under section 147(3) sentence 5 AO it does not expire while the documents matter for taxes whose assessment period has not yet ended. The Federal Chamber of Tax Advisers gives as an example the adjustment period for input tax deduction on land and buildings. Under section 15a(1) UStG it is ten years. For building projects that is relevant. Which period applies to an invoice is for the tax adviser to decide.

Separately from tax law, claims for defects in buildings and in planning and supervision services become time-barred five years from acceptance (section 634a of the Civil Code, BGB). No retention duty follows from that. It does make sense, though, not to delete a project’s billing documents earlier. That is the author’s reflection and not a requirement from the sources.

How it is archived

Under section 14(3) UStG, the authenticity of origin, the integrity of content and the legibility of the invoice must be ensured, and under section 14b(1) sentence 2 UStG for the whole retention period. Each business decides how. It may do so through internal control procedures that create a reliable audit trail between invoice and service. The GoBD add several points:

• A posting or record may not be changed in such a way that the original content can no longer be determined (margin no. 107). Unalterability can be achieved through hardware, software or organisation, for instance unalterable media, locks, logging, versioning or an access-rights concept. Simply storing files in a file system does not normally meet it unless further measures are added (margin no. 110).
• Incoming vouchers must be kept in the format in which they were received, for e-invoices that is XML (margin no. 131). Conversion, for instance into an in-house format, is governed by margin no. 135: in principle both versions are archived under the same index, and the converted one is marked as such. The converted one alone suffices if nothing is changed, no information that must be retained is lost, and the lossless conversion is recorded in the procedural documentation. If you want to be safe, also keep the original.
• Every business transaction must be based on a voucher with a unique voucher number, for example an index or a document ID (margin no. 77).

For VAT purposes it also holds that storage outside a GoBD-compliant data processing system alone is no breach of section 14b UStG, while the GoBD continue to apply for other tax purposes (BMF 2025, margin nos. 60 and 61). What follows for your archive is a question for the tax adviser.

The location of the archive matters too. Under section 14b(2) UStG, invoices are to be kept in Germany. With electronic storage that fully ensures online access, downloading and use of the data, they may also be kept in the rest of the EU; the tax office must then be told where they are kept. For storage outside the EU, paragraph 5 refers to section 146(2b) AO. With a cloud archive, clarify the provider’s location; your tax adviser says what applies.

On the GoBD version: the margin numbers come from the letter of 28 November 2019 as printed in the official Fiscal Code handbook (2023) and from the amendment of 14 July 2025; the amendment of 11 March 2024 concerns other margin numbers. The Ministry’s overview lists no later amendment on 13 November 2026. No official consolidated version was retrievable.

Procedural documentation

For every data processing system the GoBD require clearly structured procedural documentation from which the content, structure, sequence and results of the procedure are evident (margin no. 151). It normally consists of a general description, a user documentation, a technical system documentation and an operating documentation (margin no. 153). Its scope depends on the complexity of the business. Changes must be traceable, for instance through versioning. The documentation itself is kept for as long as the records it is needed to understand (margin no. 154).

For an e-invoice archive, building blocks from the Federal Chamber of Tax Advisers can be adopted: the filing system with an index, the access rights, regular backups with spot checks on whether files match the backup in number, name, size and date, and the rules for deletion. Nothing is deleted before the period ends, and only after approval by the people responsible. Whether your documentation suffices is for the tax adviser to check.

Assigning to the building project

An invoice does not always carry a project number. Assigning it to the building project helps with approval and later with billing. The assignment belongs in the index and not in the file: the data set stays unchanged, and project number, trade and approval are recorded next to it. The Federal Chamber of Tax Advisers recommends that accounting and the document archive can reach the data set in both directions through links or a unique reference, such as the incoming invoice number.

An AI can propose the assignment, based on order number, project number in the reference, or supplier and trade. It may choose only values from your project list and must be able to report “unclear”. The site manager confirms. The proposal is stored in the index and does not change the archived file. A checksum per file makes later changes visible; that is a technical suggestion and not a requirement from the sources. How a project archive as a whole can be made searchable is described in the article Searchable project files: a knowledge base with AI.

Invoices contain personal data, such as the names of sole traders and bank details. Such an archive can be operated in line with the GDPR if access, deletion periods and service providers are regulated. Your data protection officer clarifies that.

What you can do now

1. Ask your tax adviser where the data set and its attachments should be stored unalterably, and who runs the archive.
2. Check whether your current filing system prevents or logs changes, and whether data sets are kept in the format received.
3. Fix an index scheme: invoice number, date received, supplier, project number, approval.
4. Write a short procedural documentation covering route in, checking, storage location, access rights, backup and deletion rule.

General information, not legal or tax advice. Your tax adviser clarifies the individual case. As of 13 November 2026.