PDF · 8 min read
PDF/A for Archiving: When You Need It and How to Create It
A contract from 2018, a tax document from 2020: will they open in ten years exactly as they do today? With an ordinary PDF that is not guaranteed. It may refer to fonts that are missing on the reader's computer, to colour definitions that different software interprets differently, or to content that is not even inside the file. PDF/A was designed to rule out precisely these dependencies.
This guide explains what PDF/A is, which variant suits which purpose, when an archival format is actually required in Germany, and when converting can even do harm. Status: October 2026.
What PDF/A does differently
PDF/A is a family of standards (ISO 19005) for long-term archiving. It forbids anything that makes a document's appearance depend on outside circumstances: all fonts must be embedded, colours must be defined device-independently through a colour profile, JavaScript, external content and encryption are not allowed, and metadata is stored in the standardised XMP format.
A PDF/A file is still an entirely normal PDF. It opens in every reader, looks the same as before and prints as usual. It simply follows stricter rules so that it will be displayed the same way decades from now.
That stability comes at a price. A PDF/A file is a finished state: it is meant to be kept, not edited further, and anything the standard forbids is removed during conversion rather than preserved.
The variants: 1, 2, 3 and the letters a, b, u
The number refers to the part of the standard. PDF/A-1 is based on PDF 1.4 and is very restrictive, for instance it does not allow transparency. PDF/A-2 is based on PDF 1.7 and allows transparency, JPEG 2000 images and embedding other PDF/A files. PDF/A-3 additionally allows attachments of any kind, which is what ZUGFeRD relies on to embed its invoice XML. PDF/A-4 is based on PDF 2.0.
The letter describes the conformance level. b (basic) guarantees the visual appearance. u additionally requires that all text can be mapped reliably to Unicode, so it can be searched and copied dependably. a (accessible) also requires a tag structure for accessibility. In practice, PDF/A-2b is the most widely used compromise: modern enough for today's documents and achievable from almost any PDF.
- PDF/A-1: the oldest part, very strict
- PDF/A-2: transparency allowed, the common standard
- PDF/A-3: any attachments, the basis of ZUGFeRD
- b = appearance, u = Unicode text, a = accessible
Is PDF/A required? Tax office, courts, authorities
German businesses have no general obligation to store documents as PDF/A. Section 147 of the Fiscal Code (AO) requires tax-relevant records to be kept in an orderly way: books and annual financial statements for ten years, accounting vouchers such as invoices for eight years, and business correspondence for six years, each counted from the end of the calendar year. Records kept electronically must be available throughout the period, readable without delay and machine-evaluable. The law does not prescribe a file format, but PDF/A is a proven way to keep your own documents readable over the years.
There is an important limit. Under the German VAT Application Decree, received invoices must in principle be kept in the format in which they were received, and for e-invoices at least the structured part must be kept unaltered. A PDF/A copy can complement the original, but it cannot replace it.
For German courts, the Electronic Legal Transactions Regulation (ERVV) applies: briefs must be filed as PDF, and the permitted PDF versions are set out in a federal government notice published on justiz.de. Some authorities and archives explicitly require PDF/A. Check the requirements of the body you are filing with.
When converting does harm
PDF/A-2 does not allow arbitrary attachments. Converting a ZUGFeRD or Factur-X PDF to PDF/A-2b therefore loses the embedded XML, which is exactly the part that makes it an e-invoice. Toolula removes attached files during conversion and lists this in the result under Removed for PDF/A. E-invoices are already PDF/A-3 and should be archived unchanged.
Digitally signed PDFs do not survive conversion either: any change to the file invalidates the signature. Archive such documents in their original form. And only convert forms you still want to fill in once they are finished, because PDF/A is meant to be an end state.
Creating and checking PDF/A
The best route is to export directly as PDF/A from the application that created the document, because all fonts are available there. If you only have the PDF, use PDF to PDF/A. Under Method, choose Keep text: text stays selectable and searchable as long as all fonts are embedded. Toolula adds the sRGB colour profile and XMP metadata and removes what PDF/A forbids, namely JavaScript, attached files, XFA form data, automatic actions and media annotations.
If the text cannot be kept, the tool names the reason, for example Font not embedded with the font name, or CMYK colour without a CMYK profile, and offers Convert pages to images instead. That method always works, at about 150 dpi, but the text can no longer be selected afterwards. Unlock password-protected PDFs with Unlock PDF first.
The result is a PDF/A-2b file. For a formal validation report, use the free veraPDF validator. Keep the original and the archive copy together. The conversion runs entirely in your browser, so contracts and tax records are never uploaded.
Frequently asked questions
Do I have to archive my invoices as PDF/A?
No, German law does not prescribe a specific format. Received invoices should in principle be kept in the format received, and e-invoices with their unaltered XML. For documents you create yourself, PDF/A is a sensible way to keep them readable throughout the retention period.
Which PDF/A variant should I choose?
PDF/A-2b is the best compromise for most purposes and is widely accepted by archives and portals. You only need PDF/A-3 for attachments such as ZUGFeRD, and the a and u levels only when accessibility or guaranteed text search is required.
Why is my e-invoice XML gone after conversion?
PDF/A-2 does not allow arbitrary attachments, so the conversion removes attached files. A ZUGFeRD invoice is already PDF/A-3; archive it unchanged.
How do I check whether a file really is PDF/A?
With a validator such as the free veraPDF. It checks the file against the standard and produces a report you can keep alongside the document.
How long do I have to keep records in Germany?
Under section 147 AO: books and annual financial statements ten years, accounting vouchers such as invoices eight years, business correspondence six years. The period starts at the end of the calendar year in which the record was created.