PDF/A Explained: Why Standard PDF Is Not Enough for Long-Term Archiving

PDF/A is an ISO-standardised file format specifically designed for the long-term archiving of documents. Unlike standard PDF, PDF/A ensures that a document looks exactly the same and remains readable in 10, 20, or 30 years as it did at the time of storage — regardless of the software used, the operating system, or the installed fonts.

Many businesses archive their documents as standard PDF, assuming that is sufficient. In practice, this carries significant risks: missing fonts, unsupported JavaScript, encrypted files that can no longer be opened in 20 years. PDF/A eliminates these risks through strict requirements on file content.

This article explains the difference between PDF and PDF/A, compares the three most important variants, and shows how businesses can convert and validate existing documents.

Why Standard PDF Is Not Enough for Long-Term Archiving

The five biggest risks when archiving with standard PDF

1. Missing Fonts

Standard PDF can reference fonts instead of embedding them. If the referenced font is not installed on the viewer's system, a substitute font is used — the document looks different from what was intended. In court proceedings or tax audits, this can jeopardise the evidentiary value. PDF/A requires all fonts to be fully embedded.

2. JavaScript and Active Content

Standard PDF can contain JavaScript for interactive forms, calculations, or animations. The problem: JavaScript versions change, security policies block execution, and content may no longer be displayed correctly. PDF/A prohibits JavaScript entirely.

3. External References and Dependencies

Standard PDF can reference external resources: embedded videos, linked images, external stylesheets. If these resources are no longer available, parts of the document are missing. PDF/A requires all content to be fully embedded in the document — no external dependencies.

4. Encryption

Encrypted PDF files require a password to open. In 20 years, the password may be lost, the encryption method classified as insecure, or the decryption software no longer available. PDF/A prohibits encryption that restricts access to the content.

5. Colour Spaces and Transparency

Standard PDF can use device-specific colour spaces that render differently on other systems. PDF/A requires defined colour spaces (sRGB, Adobe RGB, CMYK with ICC profile) so that colours are reproduced identically on every system.

PDF/A Variants Compared

PDF/A-1b, PDF/A-2b and PDF/A-3b — which variant for which purpose?

Variant	Standard	Key Feature	Use Case
PDF/A-1b	ISO 19005-1 (2005)	Base standard, visual reproducibility, based on PDF 1.4	Simple archiving, legacy systems
PDF/A-2b	ISO 19005-2 (2011)	JPEG2000 compression, transparency, based on PDF 1.7	Modern archiving, recommended standard
PDF/A-3b	ISO 19005-3 (2012)	Arbitrary attachments can be embedded (e.g., XML, CSV)	E-invoicing (ZUGFeRD), hybrid documents

Conformance Levels: "a" and "b"

Each PDF/A variant comes in two levels:

Level "b" (basic): Guarantees visual reproducibility. The document looks the same on every system.
Level "a" (accessible): In addition to visual reproducibility, the logical document structure (tags, reading order) is preserved. This is important for accessibility and machine readability.

Recommendation: For most businesses, PDF/A-2b is the best choice. It offers modern compression for smaller file sizes, supports transparency, and is compatible with virtually all archive systems. PDF/A-3b is only needed when attachments must be embedded — for example, for ZUGFeRD e-invoices.

Conversion and Validation

How to convert existing documents to PDF/A and verify conformance

Conversion: PDF to PDF/A

Converting a standard PDF to PDF/A involves several steps:

Embed fonts: All referenced fonts are embedded into the file
Remove JavaScript: Active content is deleted
Resolve external references: Linked resources are embedded or removed
Standardise colour spaces: Device-specific colour spaces are converted to defined standard colour spaces
Add metadata: XMP metadata (title, author, creation date) is added
Remove encryption: Password protection is lifted

Validation: Checking PDF/A Conformance

After conversion, PDF/A conformance should be validated. This checks whether the document meets all requirements of the chosen standard. Typical validation results:

Conformant: The document meets all requirements
Non-conformant: Certain requirements are not met (e.g., missing font, unembedded ICC profile)

Professional archive software like Docuflair Archive performs conversion and validation automatically during import. Documents that cannot be converted to PDF/A are flagged and presented for manual review.

Limitations of Conversion

Not every PDF can be converted to PDF/A without issues. Typical problems:

Fonts that may not be embedded (licence restrictions)
Heavily encrypted files whose password is unknown
Damaged PDF files with faulty internal structure
PDFs with embedded multimedia content (video, audio)

PDF/A in Practice: Typical Use Cases

Where PDF/A is used in everyday business operations

Invoice Archiving

Incoming and outgoing invoices must be retained for 10 years (Section 147 AO). PDF/A ensures that invoices remain readable in their original form even after the retention period expires. Combined with ZUGFeRD (PDF/A-3b with embedded XML), machine processing and visual display are united in a single file.

Contract Archiving

Contracts with long terms or statutory retention periods particularly benefit from PDF/A. If a contract needs to be presented in court in 15 years, PDF/A guarantees that the document is unchanged and fully readable.

Scan-to-Archive

When scanning paper documents, PDF/A is the target format of choice. The scan is given a searchable text layer via OCR and saved as PDF/A. This ensures both long-term readability and machine evaluability.

Email Archiving

Business-relevant emails are frequently archived as PDF/A. Email headers, text content, and attachments are combined into a single PDF/A file. This simplifies searching and ensures long-term readability.

Automatic PDF/A Conversion with Docuflair

Docuflair Archive automatically converts your documents to PDF/A format during import and archives them in an audit-proof manner with OCR full-text search and a complete audit trail. Fully on-premises.

Request Free Demo Discover Docuflair Archive

Frequently Asked Questions

Answers to the most important questions about PDF/A

What is the difference between PDF and PDF/A?

Standard PDF can contain external dependencies such as fonts, JavaScript, and links to external resources. PDF/A (ISO 19005), on the other hand, embeds all required resources, prohibits JavaScript and external references, and thus ensures that the document remains readable in its original form for decades.

Which PDF/A variant should I use?

For most use cases, PDF/A-2b is the best choice: it supports modern compression (JPEG2000) and transparency. PDF/A-3b is needed when you want to embed attachments — for example, for ZUGFeRD e-invoices with an embedded XML file.

Can I convert an existing PDF to PDF/A?

Yes, conversion is possible with professional software. Missing fonts are embedded, JavaScript is removed, transparency is processed, and metadata is added. However, conversion does not succeed with every PDF — heavily encrypted or damaged files can cause problems.

Is PDF/A required for GoBD-compliant archiving?

The GoBD do not prescribe a specific file format, but require long-term readability and machine evaluability. PDF/A meets both requirements and is therefore the de facto standard for GoBD-compliant archiving in Germany and Austria.